Download Exam Study Notes Complete

Geology 12
This booklet belongs to
___________________________________
Fall/Winter 2013
1
What is Geology?
• The word geology comes from the Greek words:
 “geo” meaning Earth
 “logos” meaning the study of
• Therefore, geology is the study of the Earth
• Even ancient civilizations had geologists. These people
were important to help the ancient people find rocks and
minerals.
• The oldest geological map on record was created by the
Egyptians 3000 years ago.
• Modern geology became a scientific field in the late 1700’s with the rise of the
Industrial Revolution.
• During this time there began a huge demand for energy and minerals such as coal,
limestone, iron and water.
• Since the 1700’s, there have been great advances
in construction and development.
• We began building mines, railways, tunnels and
canals.
• All of these advances have
enabled us to see what is
happening in the rocks and minerals below the surface.
• Since the 1800’s, there has been a explosion of information
about the geological structures and nature of Canada
• Much of this information came from the work of the
early prospectors and men like Sir William Logan of
the Geological Survey of Canada.
2
Some Branches of Geology
Palaeontology:
It deals with the morphologic characteristics, modes of preservation, taxonomic classification, and geological history of the ancient lives - both
invertebrates, vertebrates and of plants. Fossils are remains of geologically very old and ancient lives in form of entire body or hard parts, which are
calcified, and / or silicified (petrified) in form of moulds and casts or as traces of remains / relics which are preserved in various modes within
sedimentary strata.
Fossilization is a natural process. Fossils have important uses in the fields of bio-stratigraphic correlation, palaeo- climatic interpretation, top and bottom
criteria for correct stratigraphic interpretation, polaeogeographic reconstruction and economic geology field for their different utilitarian aspects.
Economic Geology:
It is the branch that deals with various geologic and geo-economic aspects of the vast array of metallic, non-metallic, industrial minerals and some
specific rocks and the fuel minerals such as petroleum, natural gas, coal, radioactive minerals and geothermal sources. This branch describes the useful
minerals (ore and nonmetallic minerals) in respect of their commercial value (metal contents) mode of occurrence, classification, grades, uses and origin.
An applied aspect of this important branch includes geological exploration, value assessment of economic deposits, mining, beneficiation, reserve
estimation and different aspects of mineral economics. The applied aspects of this branch have great bearing on the formulation of conservation
measures that leads to a National Mineral Policy for the country.
A brief description of the applied aspects of the allied branches is submitted as follows. These are less applied branches which utilise vg-% the
application of the cardinal / main branches in close conjunction with scientific disciplines other than geology viz; chemistry, physics, geography, botany,
zoology and anthropology. Also geoscience is amalgamated in some respect with humanities disciplines like History (as Ancient History and
Archeology). The formal list of applied branches having direct relation with the main branches described above is as follows.
Engineering Geology:
This applies the geologic basics to the field of engineering structures such as dams, reservoirs, tunnels, bridges and embankments, in which concepts of
geology and civil engineering are given nearly equal weightage to construct engineering structures in the most suitable and safe geologic sites
recommended by geological studies. Geologist recommends a few favourable site choices and one of them is finally selected paying equal weightage to
geo-safety and engineering feasibility of total cost factors.
Marine Geology:
This allied branch deals with the application of geological knowledge in evaluating the favourable locales in the littoral, offshore and shelf regions to
explore into the realm of marine sedimentary sites to describe the coastal geomorphologic characteristics, the presence of offshore oil and gas reservoirs
and vast mineral wealth of black sand beach placers.
Geophysics:
It relates to the study of physical properties like gravity, density, magnetism, elasticity (seismic wave behaviour), electrical and electromagnetic
behaviour and radioactivity response of the rock and mineral deposits underneath. Geophysical methods take the advantage of the deviation of the
properties from normal ground behaviour i.e. deviation from the normal values termed as "anomalies".
These methods are quickly and easily completed on the surface over large areas which can be explored economically and efficiently. Exploration
geophysics otherwise termed as geophysical prospecting methods are helpful in knowing the subsurface geological structure to help in discovering
variety of metallic minerals, radioactive deposits and petroleum traps. Resistivity methods in particular, aid in assessing the potentials of ground
(underground) water of a region.
Geochemistry:
This branch is of relatively recent application in which chemistry of earth's constituents are studied and as such it relates to the study of the occurrence,
distribution, abundance, mobility etc of different elements present in the crustal apron. In this method, geochemical anomalies detected in the ore body
and its surroundings are used to locate the variety of metallic and non-metallic economic deposits.
Hydro-geology:
Also termed as geohydrology, it deals with mode of occurrence, movements, qualitative and quantitative nature of ground water present in the zone of
saturation below the surface. The characteristics of water-bearing and conducting strata (the aquifers) are studied to assess the ground water potential in
terms of quantity and quality.
Environmental Geology:
This is the branch that relates geology to the human activity. It describes the reciprocal relation between the environment and the modern mankind. The
modern society and its detrimental effects on our ecosystem through mining, township formation deformation and other anthropogenic activities affect
the global environmental balance through pollution of air, water, land and biota.
Restoration of the environment through geological endeavours is of prime interest to the modern society. Geology plays a positive role in Environmental
Impact Assessment (EIA) and Environmental Management Plan (EMP). These aspects constitute the cardinal themes of this emerging branch.
3
The Four Spheres of the Earth
Atmosphere, Biosphere, Hydrosphere,
Lithosphere
http://video.about.com/geography/The-FourEarth-Spheres.htm
By Matt Rosenberg, About.com Guide
The area near the surface of the earth can be divided up
into four inter-connected "geo-spheres:" the lithosphere,
hydrosphere, biosphere, and atmosphere.
The names of the four spheres are derived from the
Greek words for stone (litho), air (atmo), water (hydro),
and life (bio).
Lithosphere
The lithosphere is the solid, rocky crust covering entire planet. This crust is inorganic and is composed of
minerals. It covers the entire surface of the earth from the top of Mount Everest to the bottom of the Mariana
Trench.
Hydrosphere
The hydrosphere is composed of all of the water on or near the earth. This includes the oceans, rivers, lakes, and
even the moisture in the air. Ninety-seven percent of the earth's water is in the oceans. The remaining three
percent is fresh water; three-quarters of the fresh water is solid and exists in ice sheets
Biosphere
The biosphere is composed of all living organisms. Plants, animals, and one-celled organisms are all part of the
biosphere. Most of the planet's life is found from three meters below the ground to thirty meters above it and in
the top 200 meters of the oceans and seas.
Atmosphere
The atmosphere is the body of air which surrounds our planet. Most of our atmosphere is located close to the
earth's surface where it is most dense. The air of our planet is 79% nitrogen and
just under 21% oxygen; the small amount remaining is composed of carbon
dioxide and other gasses.
All four spheres can be and often are present in a single location. For example, a
piece of soil will of course have mineral material from the lithosphere.
Additionally, there will be elements of the hydrosphere present as moisture
within the soil, the biosphere as insects and plants, and even the atmosphere as
pockets of air between soil pieces.
4
The Layers of the Earth's Crust
50 km
The Earth can be divided
into 3 major layers:
1.
2.
3.
6400 km
The Crust
The Mantle
The Core
a. The Inner Core
b. The Outer Core
The distance from the surface of the earth's crust to the center of the inner core of the earth is
6400 km.
The Crust is the outer layer of the earth. This is where we live. It is where all plants and
animals live. It includes the mountains, valleys, plains, hills, and ocean floors. The crust
contains all the minerals (like gold, silver, iron, and salt) and oil deposits (as well as natural gas
and coal) that we mine for use in many substances. The crust is a very thin layer of the entire
earth. It is only about 50 km thick in most places, but can be as thin as 6 km under the oceans. It
can be as thick as 90 km around mountain ranges. The crust is made up of solid rock, soil, sand
and the plants, animals and oceans that cover the surface. Earthquakes take place in the crust.
The mantle is the layer just beneath the crust. The mantle is about 2900 km thick. The part
closest to the crust is fairly solid, but the part closer to the center of the earth is more liquid and
can flow slowly. The mantle is made up of melted rock. When this melted rock is under the
surface of the earth, it is called magma. When it bubbles up onto the surface, we call it lava. The
mantle, which is made of iron (Fe), magnesium (Mg), aluminum (Al), silicon (Si), and oxygen
(O) silicate compounds. The temperature there is over 1000oC.
The outer core is a so hot that all the rock and metals here are completely liquid. This layer is
made up of liquid iron and sulfur. This layer is about 2200 km thick. It's temperature is about
3700oC.
The inner core is also very hot (4300oC). However, the pressure here is so high that the iron is
no longer a liquid, it is now squeezed into a solid core of iron. This layer is about 1250 km from
the outer edge to the center of the core. It is so hard that no machine on earth, if we could ever
reach it, could even make a dent in the layer.
5
The Story of Alfred Wegener
Alfred Wegener was a German scientist who was studied to be an
astronomer (someone who studies Outer Space). He never worked as an
Astronomer, though. Instead he spent most of his life working as a
meteorologist (a scientist who studies weather). Through his work he
became an amazing explorer. He spent much of his life in Greenland
studying Arctic climate. He was a “true scientist” because wherever he went, he was always looking for new
ways to explain the world around him.
He was the first person to suggest (1910) that the continents of the world were moving and at once were all
squished together as one Super-Continent. He called this idea “The Theory of Continental Drift”. One of
the first clues to his theory came from looking at the shape of the continents. He noted that they look like
they could fit together, like pieces of a jigsaw puzzle.
Wegener also found evidence to support his theory in geology (study of rocks
and minerals) and palaeontology (study of fossils). He found the fossil of a small,
extinct reptile in both South America (Brazil) and southern Africa.
Wegener knew that this reptile was too small to be able to
swim across the Atlantic. This means that those two
continents must have one day been touching in order for the
lizards to be in both places. Another bit of evidence he
found we the fossils of tropical ferns up in the Arctic. There is no way that those
topical plants could ever live that far north. Therefore, he thought that those northern
areas must have been down nearer the equator at some point in history.
He named the supercontinent, Pangaea [pan-GEE-uh]. Pangaea is a
word that means “all the earth”. In 1912, Wegener wrote about his
theory in a book called, The Origins of Continents and Oceans.
A Rude Response
Other scientists did not believe in Wegener’s theory. They made fun of him and talked to him and about him
in a very disrespectful way. They told Wegener that he should not concern himself with geology when he
was “only a weatherman”.
Most scientists at that time believed that there had once been long land-bridges that connected the
continents. This explained how the lizards crossed from one continent to the other.
Despite this bad treatment by the other scientists of the time, he continued to explore the idea of continental
drift and revise his book three times.
6
Heroic to the End
In 1930 Wegener returned to Greenland. He was the expedition leader of 21 scientists and technicians.
They were there to study the great ice cap and its climate. Wegener and his team needed to set up three
“camps”, one on the coast (called Base Camp), one in the middle of Greenland (called Middle Camp)
and one on the far coast.
From the beginning, things went badly. The team’s boats arrived at Greenland on April 15, but could
not get into the harbour because it was jammed with ice for another 2 months. On July 15, way behind
schedule, a small team headed inland to set up the Middle Camp. It was 250 miles inland. They had a
terrible trek due to constant storms. As a result, only some of their needed supplies made it with them
to the camp. They even lost their arctic survival tent and their radio transmitter.
On September 21 Wegener himself led a 15-dogsled team to Middle Camp to try to bring them the needed supplies. With
him was his friend Fritz Lowe and 13 Greenlanders. Again terrible storms and harsh conditions slowed the team. Despite
the terrible conditions, Wegener wrote that he had to make it through as it was "a matter of life and death" for his friends at
Middle Camp. He thought the campers would be freezing without their tent and possibly starving if they had run out of
food.
The weather did not get any better however and by the time they finally reached Middle Camp, only Wegener, Lowe and
one Greenland (named Villumsen), had not given up and returned home. At Middle Camp, the travelers were shocked to
find that the campers had been survived nicely despite the missing tent as they had been able to dig an ice cave for shelter.
They had also planned out their food carefully to make sure that they could stretch their supplies through the winter. The
heroic rescue run had been unnecessary, but there had been no way to let Wegener know; remember their radio had not
made it!
Wegener’s friend, Lowe, was exhausted and his feet and fingers were badly frostbitten. Wegener, on the other hand,
"looked as fresh, happy and fit as if he had just been for a walk". Rasmus Villumsen, the 22-year-old Greenlander who had
accompanied them, was also in good shape. Two days later, on November 1, they all celebrated Wegener's 50th birthday.
Then, because supplies were short and Lowe had to stay to heal, Wegener and Villumsen, set off for the coast. Their friends
would never see them alive again.
Base camp assumed that they had stayed at Middle Camp for the winter. Eismitte. When April came with no word, they
sent out a search party to make sure. Some 118 miles inland the searchers came upon
a pair of skis stuck upright in the snow, with a broken ski pole lying between them.
On May 12, 1931, they found Wegener's body. It was fully dressed and lying on a
reindeer skin and sleeping bag. Wegener's eyes were open, and the expression on his
face was calm and peaceful, almost smiling. Apparently he died while lying in his
tent. His friends thought Wegener probably suffered a heart attack brought on by the
tremendous strain of trying to keep up with the dogsled over rough terrain. Rasmus
Villumsen (22 years old) obviously buried Wegener with great care and respect, then
continued on for the base camp, only to disappear into the white wilderness. Though
a long search was made, the Greenlander's body was never found.
Wegener's friends left his body as they found it and built an ice-block mausoleum
over it. Later they erected a 20-foot iron cross to mark the site. All have long since
vanished beneath the snow, inevitably to become part of the great glacier itself.
Newspapers praised Wegener as a hero, for putting the lives of the others before his
The last photo of Alfred Wegener and
own, but it would be some years before scientists began to respect his
Rasmus Villumsen, taken on 1 November
groundbreaking theory. Scientists now know that huge plates, several miles thick, lie
1930 (Wegener's 50th birthday) as they
under Earth’s continents and oceans. As heat rises from deep underground, the plates
were leaving the "Eismitte" Station.)
move. This action, known as plate tectonics, explains how the continents have drifted apart in the past and continue to drift
today. Wegener had some of the details wrong, but his basic idea was correct – and way ahead of its time!
7
J. Tuzo Wilson: Discovering transforms and hotspots
Canadian geophysicist J. Tuzo Wilson was also pivotal in advancing the plate-tectonics theory. Intrigued
by Wegener's notion of a mobile Earth and influenced by Harry Hess' exciting ideas, Wilson was eager to
convert others to the revolution brewing in the earth sciences in the early 1960s. Wilson had known Hess in
the late 1930s, when he was studying for his doctorate at Princeton University, where Hess was a dynamic
young lecturer.
J. Tuzo Wilson (1908-1993) made major contributions to the
development of the plate-tectonics theory in the 1960s and 1970s.
He remained a dominant force in the Canadian scientific scene
until his death. (Photograph courtesy of the Ontario Science
Centre.)
In 1963, Wilson developed a concept crucial to the plate-tectonics theory. He suggested that the Hawaiian
and other volcanic island chains may have formed due to the movement of a plate over a stationary
"hotspot" in the mantle. This hypothesis eliminated an apparent contradiction to the plate-tectonics theory -the occurrence of active volcanoes located many thousands of kilometers from the nearest plate boundary.
Hundreds of subsequent studies have proven Wilson right. However, in the early 1960s, his idea was
considered so radical that his "hotspot" manuscript was rejected by all the major international scientific
journals. This manuscript ultimately was published in 1963 in a relatively obscure publication, the Canadian
Journal of Physics, and became a milestone in plate tectonics.
Another of Wilson's important contributions to the development of the plate-tectonics theory was published
two years later. He proposed that there must be a third type of plate boundary to connect the oceanic ridges
and trenches, which he noted can end abruptly and "transform" into major faults that slip horizontally. A
well-known example of such a transform-fault boundary is the San Andreas Fault zone. Unlike ridges and
trenches, transform faults offset the crust horizontally, without creating or destroying crust.
Wilson was a professor of geophysics at the University of Toronto from 1946 until 1974, when he retired
from teaching and became the Director of the Ontario Science Centre. He was a tireless lecturer and
traveller until his death in 1993. Like Hess, Wilson was able to see his concepts of hotspots and transform
faults confirmed, as knowledge of the dynamics and seismicity of the ocean floor increased dramatically.
Wilson and other scientists, including Robert Dietz, Harry Hess, Drummond Matthews, and Frederick Vine,
were the principal architects in the early development of plate tectonics during the mid-1960s -- a theory
that is as vibrant and exciting today as it was when it first began to evolve less than 30 years ago.
Interestingly, Wilson was in his mid-fifties, at the peak of his scientific career, when he made his insightful
contributions to the plate-tectonics theory. If Alfred Wegener had not died at age 50 in his scientific prime,
the plate tectonics revolution may have begun sooner.
8
Geologic Activity Away from Plate Boundaries
The boundaries described above account for the vast majority of seismic and volcanic activity on the
earth. The more data that began to fit into the plate tectonics model, however, the more the
exceptions stood out. What could account for Hawaii, for example, a scene of long-lived volcanic
activity in the middle of the Pacific plate far from plae boundaries?
There had to be something else. In 1963, J. Tuzo
Wilson, a Canadian geophysicist, theorized that the
mantle contained immobile hotspots, thin plumes of
hot magma that acted like Bunsen burners as plates
moved over them. The Hawaiian Islands form a long,
linear chain, with ongoing volcanic eruptions on the
island of Hawaii and extinct, highly eroded volcanic
islands to the northwest. According to Wilson's
hotspot theory, the chain of islands represents the
southeastward motion of the Pacific plate over a mantle plume.
J. Tuzo Wilson's original sketch of the
Hawaiian hot spot.(Used with the
permission of the Canadian Journal of
Physics).
One important implication of Wilson's theory was that because hotspots were stationary, hotspot
tracks could be used to trace plate motion history. For example, the track of the Hawaiian chain
continues to the northwest as an underwater chain of progressively older, no longer active volcanoes.
Once the volcanic eruptions stop, ocean waves begin to take their toll, eroding the islands down to just
below sea level, at which point they are called seamounts. The islands and seamounts associated with
the Hawaiian hotspot provide a history of motion for the Pacific plate, which appears to have taken an
eastward turn around 28 million years ago. Other hotspot tracks around the world can be used in a
similar manner to reconstruct a global plate tectonic history.
What Are the Driving Forces?
Hotspots added further proof to confirm that plates move constantly and steadily. What ultimately
drives plate motion? Plates are constantly shifting and rearranging themselves in response to each
other. Eventually, a new Pangaea (or single supercontinent) will form, break apart, and form again
on the earth. What keeps these plates moving?
Hess assumed that mantle convection was the main
driving force - hot, less dense material rises along
mid-ocean ridges, cools, and subsides at subduction
zones, and the plates "ride" these convection cells.
Though there is little doubt that convection does
occur in the mantle, current modeling suggests that
it is not so simple. Many geologists argue that the
force of convection is not enough to push enormous
"Ridge push" and "slab pull" are both ways that
lithospheric plates like the North American plate.
gravity can act to keep a plate in motion. Note
They suggest instead that gravity is the main driving
that arrows on convection cells and overlying
plate are going in the same direction.
force: cold, dense oceanic crust sinks at subduction zones,
Figure modified from This Dynamic Earth, a
pulling the rest of the plate with it. According to this theory,
publication from the U.S. Geological Survey.
magmatic intrusions at spreading ridges are passive - the
magma merely fills a hole created by pulling two plates apart.
The strength of plate tectonic theory lies in its ability to explain everything about the processes we
see both in the geologic record and in the present.
9
Plate Tectonics – The Moving Crust
The surface of the earth (the crust) is not one solid continuous covering (like an egg shell).
Instead, it is broken into many smaller areas known as PLATES. It is more like a hard boiled
egg that has been dropped and the shell have cracked in many places. The map below shows the
major plates of the earth's surface.
The name of the plate where you live is called "The __________________________ Plate".
All of these plates are constantly moving very slowly over the surface of the earth. The
movement of the plates causes some plates to be coming toward each other, some to be moving
away from each other and others to be sliding past each other. These different types of motion
cause different effects on the earth: mountain building, volcano formation, new land formation,
and earthquakes.
The movement of the plates is caused by the flowing of the
heated magma in the mantle. How? As the magma closer to the
core becomes hot, it rises toward the crust and the cooler
magma closer to the surface of the earth falls toward the core.
This up and down, circular motion is called a convection
current. Convection currents force the plates to be pushed
along the surface in various directions.
10
Plate Boundaries
Divergent Plate Boundaries
 Plates move apart.
When 2 Oceanic Plates Diverge:
 The crust cracks and magma bubbles
between the plates, rises up to form
ridges and solidifies.
 This is known as seafloor spreading.
When 2 Continental Plates Diverge:
 When two continental plates diverge, a valleylike rift develops.
 This rift is a dropped zone where the plates are pulling apart.
 As the dropped zone widens and thins, valleys
and volcanoes form.
 Early in the rift formation, streams and rivers
flow into the low valleys and long, narrow lakes
can be created
 Eventually, the crust may become thin enough
that a piece of the continent breaks off, forming a
new tectonic plate.
 At this point, water from the ocean will rush in,
forming a new sea or ocean basin in the rift zone.
11
Convergent Plate Boundaries
 Plates move toward one another.
Type 1:
When an Oceanic Plate Converges with a Continental Plate:





Oceanic crust tends to be denser and thinner than continental crust.
The oceanic crust gets pushed under the continental crust. This is called “subduction”.
This forms a subduction zone.
The sinking crust creates a deep sea trench, or valley, at the edge of the continent.
The crust continues to be forced deeper into the earth, where high heat and pressure the crust to melt
& then rise.
 When this magma finds its way to the surface through a vent in the crust, the volcano erupts.
 An example of this is the band of active volcanoes that encircle the Pacific Ocean, often referred to
as the Ring of Fire.
Type 2:
When 2 Oceanic Plates Converge:
 When two oceanic plates collide, the older plate is forced below the younger plate.
 This creates another subduction zones.
 This creates a chain of volcanic islands known
as island arcs.
 Examples include the Mariana Islands in the
western Pacific Ocean and the Aleutian Islands,
off the coast of Alaska.
12
Tsunamis (occur with Type 2 Convergence A Lot)
 The collision and subduction of plates creates large, powerful earthquakes.
 Earthquakes generated in a subduction zone can also give rise to tsunamis.
 A tsunami is a huge ocean wave caused by a sudden shift on the ocean floor.
 If the wave reaches land, it can cause incredible destruction, like the Asian Tsunami, which killed
more than 200,000 people in 11 countries across the Indian Ocean region in December 2004.
Type 3:
When 2 Continental Plates Converge:
 A collision between two continental plates crunches and folds the rock at the boundary, lifting it up
and leading to the formation of mountains and mountain ranges.
 An example of this mountain-building process is the Himalayan range in southern Asia.
 The Himalayas were formed by the collision of the Indian and Eurasian Plates.
 Its best known peaks, Mount Everest and K2, are among several mountains that measure over 8,000
meters high at their summits.
 Since the Indian Plate is continuing in its northward movement into Asia, the Himalayas continue to
grow higher each year by small amounts (5 to 20 mm or 1 inch per year).
13
Transform Plate Boundaries
 Two tectonic plates grind past
each other in a horizontal
direction.
 This kind of boundary results in
a fault — a crack or fracture in
the earth's crust that is associated
with this movement.
Faults and Earthquakes
 Faults produce many
earthquakes.
 As the plates grind past each other, the jagged edges "lock" together for a time.
 Stress builds up at the fault line.
 A lot of energy is released when the plates suddenly slip into new positions.
 The sudden movement is what we feel as the shaking and trembling of an earthquake.
EarthQuakes – The Movers & Shakers!
Well, we know that the earth’s surface is in constant motion.
Usually the movement is so slow and gentle that we don’t notice
it. Occasionally, however, the movement occurs in such a
violent way that major vibrations travel through the land – we
know these movements as “Earthquakes”!
Earthquakes can be felt almost anywhere on the Earth, though
there are definitely areas where they are much more likely to occur. Earthquakes can feel as
gentle as a mild vibration, like you might feel if a big truck drives by your villa. They can also
shake the ground so hard that it is almost impossible to stand upright and buildings are torn
apart.
Earthquakes are most likely to happen at the boundaries between tectonic plates. They don’t
happen all the time at all boundaries though. Scientists think that they occur when two plates
become “locked” or stuck together. Convections currents down in the mantle are still pushing
them, trying to make them move, but they are stuck together and can’t move. Eventually the
rocks can’t take the pressure and the suddenly break apart. This sudden break releases a lot of
energy that travels along through the rocks as vibrations and waves known as seismic waves
(from the Greek word “seismos” meaning “earthquake”). When you feel an earthquake, you are
14
actually feeling the waves traveling through the earth that cause the land to move up and down,
just as if you were standing on the ocean!
Earthquakes can take place right in the middle of a tectonic
plate too, though this happens much less often. In the center of
a plate there are occasionally cracks in the rocks called
“faults”. When the pressure builds up underground due to the
pressure from the moving plates, it can build up to the point
where the rocks are forced to shift and break apart. This
causes the earth to shake!
The place where the rock actually breaks and moves is called
the focus of the earthquake. The point on the surface of the
earth directly above the focus is called the epicenter of the
earthquake (“epi” means above). Scientists who study
earthquakes often try to predict the location of the epicenter.
The location of the epicenter can give you a good idea of how
dangerous an earthquake might be. For example, if the
epicenter is in the middle of the Empty Quarter (desert) the
effects are unlikely to cause a lot of damage to property or
loss of life. If the epicenter is in the middle of a city, there could be devastating results
(collapsed building and thousands of deaths)!
The length of time an earthquake lasts also has an effect on how damaging the earthquake will
be. Most earthquakes only last for a minute or so, but some can last for many minutes. The
longer the quake lasts, the more damage that is likely to occur.
As we mentioned earlier, earthquakes can be felt as mild
tremors to violent, earth-splitting shakes. Scientists use
special devices called a seismograph to determine the
strength of an earthquake. Using the data from the
machine, scientists give the size of the seismic waves
measured at a particular location a magnitude number
from the Richter Scale. The Richter Scale is named after
an American scientist, Charles Richter, in 1935. The scale
starts at 0. For each increase in number by one, the
magnitude increases ten times. One of the most powerful
earthquakes to hit the earth occurred in Alaska in 1964. It measured 8.4 on the Richter Scale. It
also lasted for 4 minutes – a very long time in earthquake terms!
15
The
earthquake that caused the tsunami off the coast of Sumatra at the end of December 2004,
measured 9.0 on the Richter Scale. The movement of water caused by this earthquake caused
the deaths of almost 300 000 people spread over many countries!
Earthquake Severity (The Richter Scale)
Richter Magnitudes
Earthquake Effects
Less than 3.5
Generally not felt, but recorded.
3.5-5.4
Often felt, but rarely causes damage.
Under 6.0
At most slight damage to well-designed buildings.
Can cause major damage to poorly constructed
buildings over small regions.
6.1-6.9
Can be destructive in areas up to about 100 km
across where people live.
7.0-7.9
Major earthquake. Can cause serious damage over
larger areas.
8 or greater
Great earthquake. Can cause serious damage in
areas several hundred kilometers across.
16
Classes of Volcanoes
Volcanoes are classified under four categories




Shield or Lava Cone
Cinder Cone
Composite Cone
Lava Domes
Shield
Also called quiet or non-explosive, these are formed when great masses of lava quietly ooze out from an
opening in the earth's crust. The thin, runny lava that forms these volcanoes spread out from the hole to form
a broad, gently sloping cone. The oval, cup-shaped opening, called a crater, has a diameter of approximately
three miles.
The Hawaiian volcanoes, Mt. Loa and Kilauea are some examples. The base of Mt. Loa is so broad that the
slope is only 5 degrees.
The internal structure of a typical shield volcano
Shield volcanoes are built almost entirely of fluid lava flows. Flow after flow pours out in all directions
from a central summit vent, or group of vents, building a broad, gently sloping cone of flat, domical shape,
with a profile much like that of a warrior's shield. They are built up slowly by the accumulation of
thousands of very liquidy lava flows called basalt lava that spread widely over great distances, and then cool
as thin, gently dipping sheets. Lavas also commonly erupt from vents along fractures (rift zones) that
develop on the sides of the cone. Some of the largest volcanoes in the world are shield volcanoes. In
northern California and Oregon, many shield volcanoes have diameters of 3 or 4
miles and heights of 1,500 to 2,000 feet. The Hawaiian Islands are composed of
linear chains of these volcanoes including Kilauea and Mauna Loa on the island of
Hawaii-- two of the world's most active volcanoes. The floor of the ocean is more
than 15,000 feet deep at the bases of the islands. As Mauna Loa, the largest of the
shield volcanoes (and also the world's largest active volcano), projects 13,677 feet
above sea level, its top is over 28,000 feet above the deep ocean floor.
17
Cinder Cone
These explosive volcanoes are formed when huge blocks or rock, volcanic
bombs, cinders, and ash are hurled out of an erupting volcano and pile up on the
earth's surface. Pressure from gasses below the surface cause weakened areas of
the crust to open. The, the sudden release of gasses causes an eruption.
Unlike the lava cones, cinder cones can reach altitudes of 15,000 feet or more
above sea level and have up to 35 degree angles.
Some famous cinder cones:



Krakatoa, in Indonesia
Paricutin, in Mexico
Mt. Pelee, in Martinique
Cinder cones are the simplest type of volcano. They are built from particles and blobs of congealed
(solidifying) lava ejected (thrown out) from a single vent. As the gas-charged lava is blown violently into
the air, it breaks into small fragments that solidify and fall as cinders around the vent to form a circular or
oval cone. Most cinder cones have a bowl-shaped crater at the summit and rarely rise more than a thousand
feet or so above their surroundings. Cinder cones are numerous in western North America as well as
throughout other volcanic terrains of the world.
Schematic representation of the internal structure of a typical cinder
cone.
Parícutin Volcano, Mexico, is a cinder cone rising approximately
1,200 feet above the surrounding plain.
18
Composite Cone (AKA - Stratovolcanoes)
These consist of both lava and cinder cones. There are alternating layers of lava and cinders that indicate
that these were formed by both quiet and explosive eruptions. One of the most dangerous products of an
explosion from these volcanoes are pyroclastic flows. Pyroclastic flow is a massive cloud or surge of superheated gases filled with super-hot gases and cinders/ash. The flow can travel between 100 – 800 km per
hour. A single breath within a pyroclastic flow would incinerate a body’s internal organs. Humans and
animals overcome by pyroclastic flow are often instantly carbonized and preserved in the position in which
contact occurred.
A composite cone appears steeper than a lava cone, yet has a gentler slope than a cinder cone.
Some famous cinder cones:




Mt. Vesuvius, in Italy
Mt. Fujiyama, in Japan
Popocatepeti, in Mexico
Mt. Rainer, in Washington
Composite volcanoes
Some of the Earth's grandest mountains are composite volcanoes--sometimes called stratovolcanoes.
They are usually steep-sided, symmetrical cones of large dimension built of alternating layers of lava flows,
volcanic ash, cinders, blocks, and bombs and may rise as much as 8,000 feet above their bases. Some of the
most conspicuous and beautiful mountains in the world are composite volcanoes, including Mount Fuji in
Japan, Mount Cotopaxi in Ecuador, Mount Shasta in California, Mount Hood in Oregon, and Mount St.
Helens and Mount Rainier in Washington.
The essential feature of a composite volcano is a conduit system through which magma from a reservoir
deep in the Earth's crust rises to the surface. The volcano is built up by the accumulation of material erupted
through the conduit and increases in size as lava, cinders, ash, etc., are added to its slopes.
Schematic representation of the internal structure of a typical
composite (stratovolcano).
19
Lava domes
Schematic representation of the internal structure of a typical
volcanic dome.
Volcanic or lava domes are formed by relatively small, bulbous masses of lava too viscous (thick and
gooey) to flow any great distance; consequently, as it leaves the volcano, the lava piles over and around its
vent. A dome grows largely by expansion from within. As it grows its outer surface cools and hardens, then
shatters, spilling loose fragments down its sides. Some domes form craggy knobs or spines over the volcanic
vent, whereas others form short, steep-sided lava flows known as "coulees." Volcanic domes commonly
occur within the craters or on the flanks of large composite volcanoes.
The Novarupta Dome formed during the 1912 eruption of Katma
Volcano, Alaska.
Mont Pelée in Martinique, Lesser Antilles, and Lassen Peak and Mono domes in California are examples
of lava domes. An extremely destructive eruption accompanied the growth of a dome at Mont Pelée in 1902.
The coastal town of St. Pierre, about 4 miles downslope to the south, was demolished and nearly 30,000
inhabitants were killed by an incandescent, high-velocity ash flow and associated hot gases and volcanic
dust.
20
Giant Caldera (Supervolcano)
Two important types of volcano are difficult to recognize,
especially when they are very large. The first of these is
the "giant caldera" (see left). Calderas, which are simply
circular depressions, are found on the summits of many
volcanoes. "Giant" calderas are the largest of these: huge
craters up to many tens of miles across. Giant Calderas
form by collapse (see animation) in gigantic eruptions that
spew volcanic rocks out hundreds or even a thousand
miles in all directions. Sometimes the calderas are so filled
with lava and volcanic ash that there is no recognizable
depression at all. These can only be found by carefully
locating the big fractures or "faults" in the ground that
mark the edges of the caldera. One such caldera nearly fills Yellowstone National Park. In other
cases, the edges of the caldera remain as large cliffs or ridges surrounding the central
depression. However, the depression is so large that a person standing in the middle of it could
hardly see the edges and would only recognize them if they were pointed out. These giant
calderas can best be seen in images taken from space, like the one of the Valles Caldera in New
Mexico (below,left).
21
How a supervolcano can threaten Earth - CNN.com
By Amanda Sealy , CNN
updated 10:27 AM EDT, Thu August 30, 2012
What exactly is a "supervolcano" or a "supereruption?" Both terms are fairly new and favored by the media more than scientists, but
geologists have begun to use them in recent years to refer to explosive volcanic eruptions that eject about ten thousand times the quantity
of magma and ash that Mount St. Helens, one of the most explosive eruptions in recent years, expelled.
It’s hard to comprehend an eruption of that scope, but Earth’s surface has preserved distinctive clues of many massive supereruptions.
Expansive layers of ash blanket large portions of many continents. And huge hollowed-out calderas – craters that can be as big as 60
miles (100 km) across left when a volcano collapses after emptying its entire magma chamber at once – serve as visceral reminders of
past supereruptions in Indonesia, New Zealand, the United States, and Chile.
The eruption of these prehistoric supervolcanoes has affected massive areas. The magma flow of Mount Toba in Sumutra, which erupted
some 74,000 years ago in what was likely the largest eruption that has ever occurred, released a staggering 700 cubic miles (2,800 cubic
km) of magma and left a thick layer of ash over all of South Asia. For comparison, the quantity of magma erupted from Indonesia’s Mount
Krakatau in 1883, one of the largest eruptions in recorded history, was about 3 cubic miles (12 cubic km).
Volcanologists continue to seek answers to many unanswered questions about supervolcanoes. For example, what triggers their
eruptions, and why do they fail to erupt until their magma chambers achieve such enormous proportions? How does the composition
compare to more familiar eruptions? And how can we predict when the next supervolcano will erupt?
But there’s one thing that all experts agree on: supereruptions, though they occur, are exceedingly rare and the odds that one will occur in
the lifetime of anybody reading this article are vanishingly small.
The most recent supereruption occurred in New Zealand about 26,000 years ago. The next most recent: the cataclysmic eruption of Mount
Toba happened about 50,000 years earlier. In all, geologists have identified the remnant of about 50 supereruptions, though teams are in
the process of evaluating a number of other possibilities.
That may sound like a large number. However, when one group of scientists used the count of all the known supervolcanoes to calculate
the approximate frequency of eruptions, they found that only 1.4 supereruptions occur every one million years.
That’s not to say that a supervolcano will occur every million years at regular intervals. Many millions of years could pass without a
supereruption or many supervolcanoes could erupt in just a short period. The geological record does suggest supervolcanoes occur in
clusters, but the clusters are not regular enough to serve as the basis for predictions of future eruptions.
Scientists have no way of predicting with perfect accuracy whether a supervolcano will occur in a given century, decade, or year – and that
includes 2012. But they do keep close tabs on volcanically active areas around the world, and so far there’s absolutely no sign of a
supereruption looming anytime soon.
22
Types of Lava
Volcanoes come in many shapes and sizes. Volcanic eruptions may be quiet outflows of lava
which are so peaceful that one can stand close enough to toss in pebbles (or leis; see figure) or
so explosively violent that they blow mountains apart and blast everything within a hundred
miles to smithereens (not recommended for close observation). Both the shapes of volcanoes
and the violence of volcanic eruptions depend on the same rather mundane thing: the physical
properties of erupting lavas.
The two most important properties of lava are its viscosity, and the amount of gases dissolved in
the liquid rock. Let's look at each of these separately.
Viscosity is a term that describes the fluidity or "runniness" of the
lava. Some lavas are very "runny," not quite like water, but more
like warm honey or hot wax. When these lavas erupt, they flow
for large distances before cooling enough to turn solid. You can
imagine what kind of volcanic mountain you could make with
runny lavas by thinking about (or carefully doing) pouring hot
wax on a large sheet of paper. The wax spreads out into a large,
flat layer. Let it cool and harden and then pour another layer. The
second "flow" of wax will partly pond on the first and partly run
off onto the paper to form another flat layer. If you keep pouring
more and more "flows," you will get a large, but almost flat pile
of wax. Therefore, many small eruptions of runny lavas form
large, almost flat mountains like shield volcanoes. Eruptions of huge amounts of really runny
lavas form flood basalt type volcanoes.
23
Weathering & Erosion – What’s the Difference
Weathering involves two processes that often work in
together to decompose rocks. No movement of the rock
particles are involved in weathering. The particles that are
loosened from the main rock do not move anywhere. There
are two types of weathering:
Chemical weathering
Notice her missing nose
and facial features!
involves a chemical change in
at least some of the minerals
within a rock. It is caused by
chemicals reacting with the
rock particles and loosening
them from the rest of the
rock. Chemical weathering can be caused by pollutants and acids that get
into the air and mix with water in the air to form substances like acid rain.
The acidic rain can cause the minerals in the rocks to be dissolved, thus
breaking down the rock into smaller particles. It can also be caused by
substances that are produced by the roots of plants and fungi. These
“plant” chemicals can also eat away at the rock particles.
Mechanical weathering involves physically breaking rocks
into fragments without changing
the chemical make-up of the
minerals within it. Mechanical
weathering can be caused by water
running over the rock continually
(like in a river or stream), water
crashing down on the rocks (like on
a beach shoreline or under a
waterfall), or water constantly
dripping onto the rock (like when it
rains or when water drips in a cave onto the rock floor). It can also be caused
by wind that whips other small particles against the rocks (like when there is a
sand storm or when there is a lot of light, small sand and rock particles on the
ground that are picked up by the wind). It can also be caused by movement
over the rock (like when humans or animals walk on a particular rock
repeatedly). It can even be caused by plants whose roots grow into tiny cracks
in the rock and force the rest of the rock to break open.
Notice the damage to
the hieroglyphs!
Erosion
Erosion is the movement of particles from the rocks after
weathering has occurred. The particles are often carried away by wind or
water.
If a particle is loosened, chemically or mechanically, but stays put, it is called weathering.
Once the particle starts moving, we call it erosion.
24
Deposition
When a river meets either standing water or nearly flat lying ground, it will deposit its load. If this happens
in water, a river may form a delta. From its headwaters in the mountains, along a journey of many
kilometers, rivers carry the eroded materials that form their stream load. Suddenly the river slows down
tremendously in velocity, and drops the tremendous load of sediments it has been carrying. Deltas are
relatively flat topped, often triangular shaped deposits of sediments that form where a large river meets the
ocean. The name delta comes from the capital Greek letter delta, which is a triangle, even though not all
deltas have this shape. A triangular shaped delta forms as the main stream channel splits into many smaller
distributaries. As the channel shifts back and forth dropping off sediments and moving to a new channel
location a wide triangular deposit forms.
Deposition
-- Rock particles are deposited somewhere else --the final step in the erosional-depositional system.


· agents of erosion become agents of deposition
· Final deposition of particles (sediments) usually occurs at the mouth of a stream--a process called
horizontal sorting takes place:
o o The sediments that were once carried down the stream are arranged from largest to
smallest.
Factors Affecting Deposition
The major factors that affect the rate of deposition are:


· particle size, shape, density, and the velocity of the transporting stream:
o o Size: smaller particles settle more slowly than the larger particles, due to gravity. The
smaller particles tend to stay in suspension for longer periods of time. This form of
deposition is called graded bedding or vertical sorting. The diagram below shows graded
bedding.
Velocity:
o o If the stream slows down during a drought period, the carrying power will decrease and the
particle sizes carried and deposited will also decrease.
o o If a stream is flowing faster due to flood conditions, then the carrying power of the stream
will increase and the sizes of particles deposited will increase as well.
Glacial Deposition
Glacial ice deposits --very different from stream (water) deposits.


Glacial deposits of gravel, boulders, and sand are unsorted with no layer as in graded bedding.
Till which is the accumulation of sediments carried by a glacier is very sharp like broken glass.
25
Rocks & Minerals Note
The Earth’s crust is made up of a complex mixture of
pure elements, minerals and rocks. The most basic
ingredients are known as elements. There are 90 known
elements that exist in the Earth’s crust. These elements
combine with one another in a number of natural ways,
creating molecules and compounds known as minerals.
There are approximately 4000 known minerals found in
the Earth’s crust, with dozens of new minerals being
discovered each and ever year.
To be considered a mineral, a sample must:
1. Occur Naturally: substances that form without any human help.
2. Be Solid: a state of matter that holds its own shape and structure.
3. Be Inorganic: substances that are not living and never were living (they aren't made
of carbon compounds like those found in living things).
4. Be Crystalline: substances that have a distinct composition and arrangement of
atoms. They have a specific crystal shape.
There are some exceptions to the above rule:
Soft Minerals
Mercury is considered a mineral, even though the metal is
liquid at room temperature. At about 40 degrees below
zero, mercury solidifies and forms crystals like other
metals. So there are parts of Antarctica where mercury is
definitely a mineral.
Organic Minerals
The rule that minerals must be inorganic may be the strictest
one. The substances that make up coal, for instance, are
different kinds of hydrocarbon compounds derived from cell
walls, wood, pollen and so on. These are called macerals
instead of minerals. But if coal is squeezed hard enough
for long enough, the carbon sheds all its other elements and
becomes graphite. Even though it is of organic origin,
graphite is a true minera l, carbon atoms arranged in sheets.
Diamond, similarly, is carbon atoms arranged in a
rigid framework.
26
Amorphous (Formless) Minerals
A few “minerals” do not have a specific crystal structure. Many minerals form
crystals that are too small to see under the microscope. But even these can be
shown to be crystalline at the nano-scale using a high-tech microscopic
technique.
But a few substances fail the X-ray test. They are truly glasses, with a fully
random structure at the atomic scale. They are amorphous, a Latin word that
means "formless." These get the honorary name mineraloid. Mineraloids are a
small club of about eight members. They include:
Amber
Jet
Obsidian
Opal
Lechatelierite
Limonite
Palagonite
Pearl
True Minerals
True minerals combine to form crystals in regular and distinct
patterns. Sometimes the crystals are obvious to the un-aided eye.
In other occasions, it is necessary to use a microscope to see the
crystals.
At the surface of the Earth we generally do not
find very much solid rock. The solid rock is
covered by several feet of ground up, weathered
rock, known as regolith, the fancy name for dirt.
However, in some cases, this solid rock does
protrude out of the ground in what is known as an
outcropping.
27
The Most Common Minerals
There are thousands of different minerals on the earth, but most rocks are made of the five
most common minerals:
Calcite
Quartz
Feldspar
Mica
Hornblende
Quartz
Calcite
Feldspar
Hornblende
Mica
Less than a dozen minerals make up most of the world's rocks. Here they are, with
their formulas.
Mineral
Approximate Chemical Composition
Plagioclase feldspar
Potassium feldspar
Quartz
Pyroxene
Biotite
Muscovite
Hornblende
Olivine
Calcite
Dolomite
NaAlSi3O8 to CaAl2Si2O8
KAlSi3O8
SiO2
(Mg,Fe)2Si2O6 (enstatite series) and
(Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6 (augite)
K(Fe,Mg)3AlSi3O10(OH)2
KAl2(Si3Al)O10(OH,F)2
(Ca,Na)2–3(Mg,Fe,Al)5[(Si,Al)8O22](OH)2
(Fe,Mg)2SiO4
CaCO3
CaMg(CO3)2
28
How are minerals identified?
There are some properties of minerals that we can use to help identify them; these include: the colour of the
mineral, the luster (or shininess) of the mineral, the streak colour the mineral leaves behind, and the
hardness of the mineral. Again, the main properties we focus on are:
Colour
Minerals come in every colour of the rainbow. Identifying the colour of a mineral
may help to narrow down the possibilities of what it is, but you will need to know
other properties to make a definite identification. The same mineral could have
more than 1 colour so this is the least informative property.
Lustre
Minerals can be shiny or dull or anywhere in between. In general, we describe the
luster of a mineral as: pearly, glassy, waxy, silky, greasy and brilliant.
Streak
When minerals are rubbed across the surface of a white ceramic tile (that has not
been glazed), it leaves behind a powdery streak of “true” mineral colour. This
colour is not always the colour that the mineral appears.
Hardness
Minerals can range from very soft to very hard. A hardness scale called the Moh’s
Hardness Scale is used to classify a mineral’s hardness.
Diamond
10
Corundum
9 
8 
Topaz
Quartz

7 
Orthoclase (Feldspar) 6


Apatite
5
Fluorite
4 
Calcite
3
Gypsum
2 
1
Talc

Moh’s 1
Moh’s 2
Moh’s 3
Moh’s 4
Moh’s 5
Moh’s 6
=
=
=
=
=
=
Moh’s 7
Moh’s 8
=
=
Moh’s 9 & 10 =
can be scratched very easily with a fingernail
can be scratched by the fingernail
can be scratched very easily with a knife
can be scratched easily with a knife
it is hard to scratch it with a knife
can’t be scratched with a knife but barely
Scratches glass
easily scratches glass
scratches glass very easily and can scratch a
steel file
cuts glass & scratches a steel file easily
Here are some common
Crystal Form –
shape of crystal,– some minerals have a number of different crystal
shapes
Specific Gravity –
how heavy it feels, heft
Cleavage –
pattern when mineral is broken – in planes or conchoidal
Tenacity -
toughness, how cohesive the mineral is, whether or not it falls apart
Transparency -
The ability to transmit light. Depending on a number of things, rocks &
minerals can also transmit light.
Gems stones are often valued on how clear, or transparent they are.
Special Properties–
magnetism, fluorescence, odour, streak, burn test, conductivity & even
taste (although you should never taste a mineral in the science lab).
29
What Are Crystals?
Crystals are solid material in which the atoms are arranged in
regular geometrical patterns. The crystal shape is the external
expression of the mineral's regular internal atomic structure.
Temperature, pressure, chemical conditions and the amount of
space available are some of the things that affect their growth.
SMOKY QUARTZ
There are literally thousands of minerals, their
crystal shape can be grouped on the basis of their
symmetry into seven systems of three dimensional
patterns.
CUBIC
Four 3-Fold Axes
TETRAGONAL
One 4-Fold Axis
HEXAGONAL
One 6-Fold Axis
TRIGONAL
One 3-Fold Axis
ORTHORHOMBIC
Three 2-Fold Axes
MONOCLINIC
One 2-Fold Axis
TRICLINIC
No Axes
30
Classifying Minerals
Mineral classification can be really challenging since there are over 3,000 different types of
minerals. Mineralogists group minerals into families based on their chemical composition.
There are different grouping systems in use but the Dana system is the most commonly
used. This system was devised by Professor James Dana of Yale University way back in 1848.
The Dana system divides minerals into eight basic classes. The classes are:
Mineral Classification
Native Elements This is the category of the pure. Most minerals are
made up of combinations of chemical elements. In this group a single
element like the copper shown here are found in a naturally pure form.
Silicates Silicates are the most widespread of the minerals. By
themselves they make up over 90% of the weight of the earth’s crust.
Most rocks are composed mainly of this class of minerals. Silicates are
made from metals combined with silicon and oxygen. “Silicate” is a
chemical term for the group that includes one atom of silicon
surrounded by four atoms of oxygen, or SiO4, in the shape of a
tetrahedron. Geochemists speak of the silica tetrahedra a lot.
Oxides Oxides form from the combination of a metal with oxygen.
This group ranges from dull ores like bauxite to gems like rubies and
sapphires. The magnetite pictured to the left is a member of this
group.
Sulfides Sulfides are made of compounds of sulfur usually with a
metal. They tend to be heavy and brittle. Several important metal ores
come from this group like the pyrite pictured here that is an iron ore.
Slufates are made of compounds of sulfur combined with metals and
oxygen. It is a large group of minerals that tend to be soft, and
translucent like this barite.
Halides form from halogen elements like chlorine, bromine, fluorine,
and iodine combined with metallic elements. They are very soft and
easily dissolved in water. Halite is a well known example of this group.
Its chemical formula is NaCl or sodium chloride commonly known as
table salt.
Carbonates are a group of minerals made of carbon, oxygen, and a
metallic element. This calcite known as calcium carbonate is the most
common of the carbonate group.
Phosphates are not as common in occurrence as the other families of
minerals. They are often formed when other minerals are broken down
by weathering. They are often brightly colored.
Mineraloid is the term used for those substances that do not fit
neatly into one of these eight classes. Opal, jet, amber, and mother of
pearl all belong to the mineraloids.
31
Gemstones
Gems, precious crystals, come in a rainbow of shapes and
colours. Mankind has long sought these precious rocks,
often delving deep into the earth. Gems are firmly rooted
in our human history. So, what are gems?
Gems are rare mineral crystals valued for their beauty.
Historically, gems have been classified as either precious
or semi-precious stones. The definitions of precious and
semi-precious stones have changed over time and
according to culture. For example, the ancient Greeks thought amethyst was a precious
stone; however, today amethyst is regarded as a semi-precious stone because we’ve found
so many of them in South America.
Today, when people talk about precious gems they are
usually referring to diamonds, rubies, sapphires, and
emeralds. Sometimes pearls (not really a mineral but still
called a gem), and opal are considered to be precious
gems. It’s all very confusing. That’s why it is better to use
other ways to classify gems.
The best way to classify gems is based on their
physical properties. Gems are made from different
chemicals and minerals. Because they are made from
different things, gems have different physical properties.
If you can figure out what a gem is made from you can
figure out what kind of gem you have. Diamonds are made
from carbon. Rubies and sapphires are made from the
mineral corundum. Emeralds are from the mineral beryl and amethysts from the
mineral quartz. Rubies have tiny amounts of the element chromium that makes
them red. Sapphires are gem quality corundum in any color other than red. Sapphires have
tiny amounts of other chemicals that change
the color of the crystal. Other gems are made
from different mineral crystals.
Remember, sapphires and rubies are made
from the same mineral. It could be confusing
to tell them apart unless you can see the color
of the gem.
Color is one way people can tell one gem from
another. However, you can’t just use color;
there are green garnets and green emeralds.
You have to use more than one test to tell one gem from another. There's a big long list of
different properties and tests for each of them. There is an entire branch of science that
studies gems. The science is called gemology and the scientists are called
gemologists. There are laboratories around the world that classify gems, and grade their
quality.
32
Famous Gems
There are many famous gems. There are some gems that are famous for their size or
their extraordinary color.
The most famous gem in the world is
the Hope Diamond. The Hope Diamond
is a very large blue-white diamond
currently owned by the Smithsonian
Museum in Washington DC, United
States. It is the second most visited
work of art in the world. The Hope
Diamond has been bought, sold and
stolen many times since it was
discovered in India. At one point it
belonged to the kings and queens of
France. It was stolen from France
during the French Revolution. The
people that stole the gem had it re-cut to disguise it then sold it in England. The Hope
Diamond was eventually sold to people in the United States who sold it to the
Smithsonian Museum. There are many who believe that this diamond is cursed. Do a
Google search to learn more about the cursed Hope Diamond.
The next most famous gems are the
so-called “Crown Jewels.” When people
talk about the “Crown Jewels,” they
are usually talking about the Crown
Jewels of the United Kingdom
specifically. The Crown Jewels are not
a pile of jewels, per se. They are the
gem studded royal regalia worn by the
king or queen of the United Kingdom
during coronation and other very rare
ceremonies. Regalia is a fancy word for
fancy clothes worn by the king or
queen. The Crown Jewels include
crowns, swords, jewellery, sceptres,
and the Koh-I-Noor. The Koh-I-Noor
was once the largest known diamond
in the world. It is a very large white
diamond.
© Crown copyright. The Crown of Queen Elizabeth
the Queen Mother. She wore it with the arches
removed at her daughter's coronation in 1953. (You
can seen the large Koh-i-noor diamond in the center
above another slightly smaller diamond.)
33
How Rocks are Formed Note
To identify a rock you start by identifying the minerals that make up the rock. However, two
rocks can be made of the same minerals but look very differently. They look different
because they were made in very different ways. The size and shape of the crystal minerals
inside the rocks can give us clues as to how the rocks were formed.
There are three main types of rocks:
Igneous
Sedimentary
Metamorphic
Igneous Rocks
The word igneous comes from the latin word
“ignis”, meaning “born of fire”. Igneous rocks
from when hot, molten rock called magma cools
and hardens. If the magma cools slowly inside
the earth, the grains and crystals inside the rock
are generally very large. If the magma comes up
to the surface and cools very fast, the grains and
crystals of minerals inside the rocks are usually
very small.
34
Sedimentary Rocks
Small particles of rocks, sand, and even shells are carried by
water and wind and settle or sink down onto the ground below it.
As more and more of these sediments pile up on top of each
other, the ones on the bottom become squeezed by the weight of
the ones above and by the weight of the water (if they are under
the oceans, lakes or rivers). Some of the minerals in the sediments
can also dissolve and re-solidify to “cement” the sediments
together. This forms layers of sedimentary rock.
You can often identify sedimentary rocks easily by looking for
layers.
Metamorphic Rocks
The word metamorphic rocks is a combination of
two Greek words: “meta” meaning change and “morph”
meaning shape. These rocks started out as igneous and
sedimentary rocks but the intense pressure and heat of the
earth’s interior changed their appearance. It may even have
caused the mineral grains to melt slightly and reform. This
makes the rocks even harder.
35
The Rock Cycle
36
Geologic Time Scale
A Time Line for the
Geological Sciences
Dividing Earth History into Time
Intervals
Geologists have divided Earth's history into a series of time intervals.
These time intervals are not equal in length like the hours in a day.
Instead the time intervals are variable in length. This is because geologic
time is divided using significant events in the history of the Earth.
Examples of Boundary "Events"
For example, the boundary between the Permian and Triassic is marked
by a global extinction in which a large percentage of Earth's plant and
animal species were eliminated. Another example is the boundary
between the Precambrian and the Paleozoic which is marked by the first
appearance of animals with hard parts.
Eons
are the largest intervals of geologic time and are hundreds of millions of years in duration. In the time scale above you can see the Phanerozoic Eon is the most recent
eon and began more than 500 million years ago.
Eras
Eons are divided into smaller time intervals known as eras. In the time scale above you can see that the Phanerozoic is divided into three eras: Cenozoic, Mesozoic and
Paleozoic. Very significant events in Earth's history are used to determine the boundaries of the eras.
Periods
Eras are subdivided into periods. The events that bound the periods are wide-spread in their extent but are not as significant as those which bound the eras. In the time
scale above you can see that the Paleozoic is subdivided into the Permian, Pennsylvanian, Mississippian, Devonian, Silurian, Ordovician and Cambrian periods.
Epochs
Finer subdivisions of time are possible and the periods of the Cenozoic are frequently subdivided into epochs. Subdivision of periods into epochs can be done only for
the most recent portion of the geologic time scale. This is because older rocks have been buried deeply, intensely deformed and severely modified by long-term earth
processes. As a result, the history contained within these rocks can not be as clearly interpreted.
Our geologic time scale was constructed to visually show the duration of each time unit. This was done by making a linear time line on the left side of the time columns.
Thicker units such as thee Proterozoic were longer in duration than thinner units such as the Cenozoic. We also have a printable version of the Geologic Time Scale as
a .pdf document. You can print this timescale for personal use.
37
How Do Geologists Know How Old a Rock Is?
by Mark Milligan
Geologists generally know the age of a rock by determining the age of the group of rocks, or formation, that
it is found in. The age of formations is marked on a geologic calendar known as the geologic time scale.
Development of the geologic time scale and dating of formations and rocks relies upon two fundamentally
different ways of telling time: relative and absolute.
Relative dating places events or rocks in their chronologic sequence or order of occurrence. Absolute
dating places events or rocks at a specific time. If a geologist claims to be younger than his or her coworker, that is a relative age. If a geologist claims to be 45 years old, that is an absolute age.
Relative Dating
Relative dating methods use geological principles to place events in chronological order.

The Law of superposition states that older beds are covered by younger beds so in a sedimentary
sequence the youngest unit is at the top.

The principle of fossil succession states that organisms evolve through time so that particular forms
can be used as age markers wherever they are found.
38

Cross-cutting relationships Cross-cutting rocks such as igneous intrusion are younger than the
rocks they cut.

Inclusions Any included pebbles and fragments must be older than the host rock containing them.

Deformation Any rocks effected by a deformation event (folding or tilting) must pre-date the
deformation episode.
Events can be ordered using the various methods discussed even when no absolute ages can be
measured. Where there is a break in sedimentation, a period of erosion or an episode of deformation, the
rock layers record the break as a surface called an unconformity. Unconformities range from minor
erosional breaks to strong angular discordances in bedding. An unconformity indicates a period where no
rock record is accumulated. They are time-breaks of indeterminate length. The last two diagrams illustrate
various kinds of unconformities.
39
Absolute Dating
The nuclear decay of radioactive isotopes is a process that behaves in a clock-like fashion and is thus a
useful tool for determining the absolute age of rocks. Radioactive decay is the process by which a "parent"
isotope changes into a "daughter" isotope. Rates of radioactive decay are constant and measured in terms
of half-life, the time it takes half of a parent isotope to decay into a stable daughter isotope.
Some rock-forming minerals contain naturally occurring radioactive isotopes with very long half-lives
unaffected by chemical or physical conditions that exist after the rock is formed. Half-lives of these isotopes
and the parent-to-daughter ratio in a given rock sample can be measured, then a relatively simple
calculation yields the absolute (radiometric) date at which the parent began to decay, i.e., the age of the
rock.
Of the three basic rock types, igneous rocks are most suited for radiometric dating. Metamorphic rocks may
also be radiometrically dated. However, radiometric dating generally yields the age of metamorphism, not
the age of the original rock. Most ancient sedimentary rocks cannot be dated radiometrically, but the laws
of superposition and crosscutting relationships can be used to place absolute time limits on layers of
sedimentary rocks crosscut or bounded by radiometrically dated igneous rocks.
Sediments less than about 50,000 years old that contain organic material can be dated based on the
radioactive decay of the isotope Carbon 14. For example, shells, wood, and other material found in the
shoreline deposits of Utah's prehistoric Lake Bonneville have yielded absolute dates using this method.
These distinct shorelines also make excellent relative dating tools. Many sections of the Wasatch fault
disturb or crosscut the Provo shoreline, showing that faulting occurred after the lake dropped below this
shoreline which formed about 13,500 years ago. As this example illustrates determining the age of a
geologic feature or rock requires the use of both absolute and relative dating techniques.
40
Top Environmental Concerns in Fracking
March 19, 2012
Stephen O’Day and Jessica Lee Reece
Hydraulic fracturing (“Fracking” for short) is the gas extraction process where large volumes of chemically
treated water and sand are injected underground to break apart gas-bearing rock formations.
As a result of recent technological innovations improving the ability to extract oil and natural gas from shale
and other rock formations, the popularity of hydraulic fracturing, or fracking, has surged, leading to new
investment opportunities and positive growth for the domestic gas and oil production industry. With the
expansion, however, has come risk and scrutiny.[1]
To help quantify and qualify those potential risks, and in response to escalating public concern, Congress
directed the U.S. Environmental Protection Agency (“EPA”) to conduct a study into the potential impacts of
fracking on drinking and ground water. A first report of results is expected by the end of 2012, with a final
report to be released in 2014.
Although the evolving industry offers many potential benefits, there are a number of environmental issues
leading to increased federal and state regulation of the industry.
(1) Water Issues: Contamination of Groundwater. There is considerable concern that fracking can lead
to contamination of groundwater as a result of spills, faulty well construction, or other means, including
disposal into underground injection wells. In 2010, residents of Pavillion, Wyoming complained about the
condition of their well water. In December 2011, EPA released a report finding that compounds associated
with fracking chemicals had been detected in the groundwater beneath the community and health officials
advised residents not to drink the water. EPA did emphasize, however, that its findings are specific to the
area due to the fact the fracking activities in Pavillion occurred below the level of the drinking water aquifer
and close to water wells, unlike other locations where drilling is more remote and fracking occurs much
deeper than the level of groundwater that would normally be used. In January 2012, EPA began testing
water supplies for 61 homes in Susquehanna County, Pennsylvania, and provided replacement drinking
water supplies to four homes where water tests raised health concerns. Both the state Department of
Environmental Protection and the driller active in the area are cooperating with the agency.
(2) Air Quality Issues. Fracking activities can lead to emissions into the air of methane, volatile organic
compounds, hazardous air pollutants, and greenhouse gases. EPA, the Department of the Interior, other
federal agencies and states are currently working to better characterize and reduce the air emissions from
fracking and their associated impacts. For example, through the Clean Construction USA program, EPA is
promoting newer, more efficient technology and cleaner fuels to increase the ways in which hydraulic
fracturing equipment and vehicles reduce emissions. Emissions from fracking may also contribute to global
climate change, according to a study performed by a group of researchers at Cornell University. However,
another group of Cornell researchers recently released a competing report claiming the previous research
overestimated leaks from fracked wells.
(3) Water Issues: Stress on Existing Water Supply. According to EPA’s senior policy counsel Robert
Sussman, the strain that heavy-volume surface and groundwater withdrawals of freshwater used in the
fracking process may be placing on water resources is one of the top concerns related to the process.
However, EPA has little authority to address such issues and regulation will be largely left to local and state
governments.
41
(4) Water Issues: Management of Wastewater. The wastewater associated with shale gas extraction can
contain high levels of total dissolved solids, fracturing fluid additives, metals, and naturally occurring
radioactive materials. Unfortunately, many municipal water treatment plants are not designed to remove
some of these contaminants. Methods for disposal of such wastewater include deep well injection, surface
impoundments for storage or disposal, recycling methods and discharge to a properly-licensed treatment
facility. However, these disposal methods are not without criticism. Following a series of earthquakes
clustered in an area less than one mile from a deep-injection well used mostly used for oil and gas fluid
waste disposal, the Ohio Department of Natural Resources began investigating. The Ohio DNR concluded
the seismic activity was likely induced by the deep injection well and, on December 31, 2011, the governor
ordered a moratorium that is still in place on six Class II deep injection wells. The Ohio DNR also
announced new regulations for the transportation and disposal of the wastewater, requiring operators to
supply extensive geological data before drilling (including the existence of known geological faults) and to
implement monitoring devices. Currently, oil and gas operators are generally not required to obtain a
National Pollutant Discharge Elimination System (NPDES) permit for stormwater discharges from fracking
sites unless there is a reportable quantity spill or the discharge causes or contributes to a water quality
violation.
(5) Disclosure of Fracking Chemicals. Five states—Colorado, Montana, Louisiana, Texas and North
Dakota—require operators to post data regarding the chemicals used in fracking with an online database, the
FracFocus Chemical Disclosure Registry. It is expected that one potential result of the EPA study into the
effect of fracking on water supply could be federal requirements for disclosure. Given this potential,
operators are well advised to maintain records regarding the usage of chemicals on a well-by-well basis.
The Real Story Behind the Fracking Debate
Posted: 07/30/2012 3:38 pm
By now, if you have any interest in water, energy, international security and politics, climate change,
environmental impacts on small communities, or any number of other issues of the day, you have seen,
heard, or read something about "fracking" -- the shorthand name for the process of hydraulic fracturing.
Are you confused by the debate over fracking?
I'm not surprised. The public debate is complex, angry, boisterous, a mix of science intertwined with
politics, and complicated by a lack of information (or even intentional disinformation) on all sides. And like
many other complex problems, the reality is often somewhere in between the extreme points of view that are
highlighted in the media, which seems less and less able to appreciate, report, and acknowledge nuance and
subtlety around complex scientific issues.
Fracking is not good or bad: it is a process to increase the production of fossil fuels, primarily natural gas,
from certain geological formations. But good or bad things can happen as a result of fracking, depending on
how it is implemented, where it is pursued, the technologies used, and the actions taken to increase its
benefits and reduce its impacts. And whether or not you support or oppose fracking depends on how those
benefits and impacts are perceived, distributed, addressed, and valued -- and whether it is in your backyard.
42
Do you benefit economically from fracking operations? Do you support U.S. energy independence and hope
that fracking will reduce U.S. imports of imported energy? Do you worry about climate change and feel that
fracking can help reduce dependence on much dirtier coal by increasing availability of cleaner burning
natural gas? Then you're likely to support expanded fracking. Some have hailed it as a game-changer that
promises increased energy independence, job creation, and lower energy prices.
But do you live in a rural community where the impacts of expanded drilling, extraction operations, and
water contamination are being felt? Do you worry that your local environmental and social costs outweigh
the economic benefits that are likely to accrue to other parties? Do you feel that U.S. national energy
priorities should be to reduce all fossil fuel combustion in favor of domestic renewable energy production?
Do you feel that regulatory oversight and environmental enforcement is insufficient to protect against the
downsides of rapid expansion of fracking operations? Then you're likely to oppose expanded fracking. And
opponents have called for a temporary moratorium or even a complete ban on hydraulic fracturing due to
concern over environmental, social, and public health concerns.
There ARE some fracking facts that are relevant (as opposed to opinion):





The U.S. uses a lot of energy, primarily fossil fuels.
We import a substantial amount of that energy at a real economic and political cost.
Natural gas contributes far less than coal to climate-changing greenhouse gas pollution (and other
pollution), per unit energy produced -- but far more than renewable energy options that can also
reduce dependence on coal.
Fracking requires substantial amounts of water and sometimes nasty chemicals (at least the way it is
practiced now).
There is growing evidence of both potential and actual threats of damages to local water resources.
The Pacific Institute has just released a new study on the issues associated with fracking, especially risks to
the nation's water resources. Authored by Heather Cooley and Kristina Donnelly, this assessment was based
on extensive interviews with a diverse group of stakeholders, including the industry itself, representatives
from state and federal agencies, academia, environmental groups, and community-based organizations from
across the United States. When honest and open discussions occur, there is surprising agreement among
them about the range of concerns and issues associated with hydraulic fracturing. The top six key concerns
were:
1.
2.
3.
4.
5.
Spills or leaks of contaminated water or fracking fluids into the surrounding environment.
Storing, transporting, treating, and appropriately treating or disposing of wastewater
Water requirements for fracking competing with other water needs in water-scarce regions.
Truck traffic and impacts on air quality in rural communities.
Lack of comprehensive and credible data and information to clearly assess the risks and develop
sound policies to minimize those risks.
6. The failure to clarify terms and definitions about the hydraulic fracturing process.
What is critically apparent is that the dialogue about hydraulic fracturing -- to the extent there has been a
dialogue rather than a series of monologues -- has been marked by confusion and obfuscation due to a lack
of clarity about the terms used, serious data and information gaps, and ideological positions. A more fruitful
and informed debate is the only thing likely to lead to appropriate energy, water, and environmental
policies. But the current debate is rarely well-informed, and even less frequently, fruitful. Can we figure out
how to reap the benefits of fracking without suffering, unnecessarily, the adverse costs? If not, opposition
will continue to grow, and it will be deserved.
43
Environmental Problems: Landfills
By Jared Skye
Landfills have led to some of the most heated, acrimonious battles over
pollution in the public commons that have ever been seen. While there are a
number of reasons for the vehement arguments that often surround landfills,
one of the largest is the juxtaposition of both the understood need for
landfills and the lack of will to live near one. According to the Environmental
Protection Agency (EPA), the average person dumps almost 4.5 pounds of
waste into landfills every single day. With the population skyrocketing across
the country, these landfills will only become more of a public issue as time
goes on. Despite the arguments over landfills in general, there are no
arguments over the assertion that there are many things that contribute to
the environmental problem of landfills.
Environmental Problems Caused by Landfills
The environmental problems caused by landfills are numerous. While there are many problems with landfills, the
negative effects are most commonly placed into two distinct categories: atmospheric effects and hydrological
effects. While these effects are both of equal importance, the specific factors that drive them are important to
understand on an individual basis.
Atmospheric Effects
According to the EPA, the methane produced by the rotting organic matter in unmanaged landfills is 20 times
more effective than carbon dioxide at trapping heat from the sun. Not only does methane get produced by the
various forms of rotting organic matter that find their way into landfills, but household cleaning chemicals often
make their way here as well. The mixture of chemicals like bleach and ammonia in landfills can produce toxic
gases that can signfiicantly impact the quality of air in the vicinity of the landfill.
Aside from the various types of gases that can be created by these landfills, dust and other forms of nonchemical contaminants can make their way into the atmosphere. This contributes further to the air quality issue
that plagues modern landfills.
Hydrological Effects
Landfills also create a toxic soup of industrial and home-cleaning chemicals. People throw away everything from
industrial solvents to household cleaners in landfills, and these chemicals accumulate and mix over time. A more
immediate concern is for the welfare of the wildlife that comes into contact with these chemicals, and it is not
uncommon for animals to suffer inconceivably painful deaths resulting from chemical contamination.
44
Additional Landfill Environmental Problems
Emissions are not the only types of problems associated with landfills. A closer look can show why so many
much needed changes are so difficult to come by.
Landfill Fires: Landfill gases, and the shear amount of landfill waste, can easily ignite a fire. Fires
can be difficult to put out and contribute to the pollution of the air and water. They can also potentially
destroy habitats nearby if not controlled soon enough. The most flammable gas that is most
commonly produced by landfills is methane, which is highly combustable. Firefighters will often use a
fire-retardent foam to fight fires in landfills due to the presence of chemicals that would not be
subdued by water, further adding to the chemical load of these landfills.
Decomposition: Sometimes, landfills are covered with earth, seeded with grass, and transformed
into recreational areas. The management of gasses coming out of these sites is a constant issue, and
creates an ongoing cost despite the new facade of the landfill. Products that are natural, such as
wasted fruits and vegetables, will decompose within weeks while No MOre Trash! reports that items
like Styrofoam can take over a million years to decompose.
A Creative Solution
A number of landfills have been in use since long before the popularity of recycling. These landfills contain a
wealth of mineral resources that are simply sitting there rotting away, and this has created a unique opportunity
for "green" American mining. Miners have bought the rights to a number of different landfill facilities to conduct
mining operations. With all of the precious metals and other minerals that are in electronic waste, more and
more companies are looking at landfills as gold mines. This extra activity comes with larger atmospheric
pollution via dust; however this is generally offset by the amount of pollution that is not being generated by
mining new materials and shipping them around the world.
WHAT IS THE COMPOSITION OF A LANDFILL?
There are four critical elements in a secure landfill: a bottom liner, a leachate collection system, a cover, and the
natural hydrogeologic setting. The natural setting can be selected to minimize the possibility of wastes escaping
to groundwater beneath a landfill. The three other elements must be engineered. Each of these elements is
critical to success.
THE NATURAL HYDROGEOLOGIC SETTING:
You want the geology to do two contradictory things for you. To prevent the wastes from escaping, you want
rocks as tight (waterproof) as possible. Yet if leakage occurs, you want the geology to be as simple as possible
so you can easily predict where the wastes will go. Then you can put down wells and capture the escaped
wastes by pumping. Fractured bedrock is highly undesirable beneath a landfill because the wastes cannot be
located if they escape.Mines and quarries should be avoided because they frequently contact the groundwater.
45
WHAT IS A BOTTOM LINER?
State-of-the-art plastic (HDPE) landfill liners are 100 mils or 1/10 of an inch thick. It may be one or more
layers of clay or a synthetic flexible membrane (or a combination of these). The liner effectively creates a
bathtub in the ground. If the bottom liner fails, wastes will migrate directly into the environment. There are three
types of liners: clay, plastic, and composite.
WHAT IS WRONG WITH A CLAY LINER?
Natural clay is often fractured and cracked. A mechanism called diffusion will move organic chemicals like
benzene through a three-foot thick clay landfill liner in approximately five years. Some chemicals can degrade
clay.
WHAT IS WRONG WITH A PLASTIC LINER?
The very best landfill liners today are made of a tough plastic film called high density polyethylene (HDPE).* A
number of household chemicals will degrade HDPE, permeating it (passing though it), making it lose its
strength, softening it, or making it become brittle and crack. Not only will household chemicals, such as moth
balls, degrade HDPE, but much more benign things can cause it to develop stress cracks, such as, margarine,
vinegar, ethyl alcohol (booze), shoe polish, peppermint oil, to name a few.
WHAT IS WRONG WITH COMPOSITE LINERS?
A Composite liner is a single liner made of two parts, a plastic liner and compacted soil (usually clay soil).
Reports show that all plastic liners (also called Flexible Membrane Liners, or FMLs) will have some leaks. It is
important to realize that all materials used as liners are at least slightly permeable to liquids or gases and a
certain amount of permeation through liners should be expected. Additional leakage results from defects such
as cracks, holes, and faulty seams. Studies show that a 10-acre landfill will have a leak rate somewhere
between 0.2 and 10 gallons per day.
WHAT IS A LEACHATE COLLECTION SYSTEM?
Leachate is water that gets badly contaminated by contacting wastes. It seeps to the bottom of a landfill and is
collected by a system of pipes. The bottom of the landfill is sloped; pipes laid along the bottom capture
contaminated water and other fluid (leachate) as they accumulate. The pumped leachate is treated at a
wastewater treatment plant (and the solids removed from the leachate during this step are returned to the
landfill, or are sent to some other landfill). If leachate collection pipes clog up and leachate remains in the
landfill, fluids can build up in the bathtub. The resulting liquid pressure becomes the main force driving waste out
the bottom of the landfill when the bottom liner fails.
WHAT ARE SOME OF THE PROBLEMS WITH LEACHATE COLLECTION SYSTEMS?
Leachate collection systems can clog up in less than a decade. They fail in several known ways: 1) they clog up
from silt or mud; 2) they can clog up because of growth of microorganisms in the pipes; 3) they can clog up
because of a chemical reaction leading to the precipitation of minerals in the pipes; or 4) the pipes become
weakened by chemical attack (acids, solvents, oxidizing agents, or corrosion) and may then be crushed by the
tons of garbage piled on them.
WHAT IS A COVER?
A cover or cap is an umbrella over the landfill to keep water out (to prevent leachate formation). It will generally
consist of several sloped layers: clay or membrane liner (to prevent rain from intruding), overlain by a very
permeable layer of sandy or gravelly soil (to promote rain runoff), overlain by topsoil in which vegetation can root
(to stabilize the underlying layers of the cover). If the cover (cap) is not maintained, rain will enter the landfill
resulting in buildup of leachate to the point where the bathtub overflows and wastes enter the environment.
46
WHAT ARE THE PROBLEMS WITH COVERS?
Covers are vulnerable to attack from at least seven sources: 1) Erosion by natural weathering (rain, hail, snow,
freeze-thaw cycles, and wind); 2) Vegetation, such as shrubs and trees that continually compete with grasses
for available space, sending down roots that will relentlessly seek to penetrate the cover; 3) Burrowing or soildwelling mammals (woodchucks, mice, moles, voles), reptiles (snakes, tortoises), insects (ants, beetles), and
worms will present constant threats to the integrity of the cover; 4) Sunlight (if any of these other natural agents
should succeed in uncovering a portion of the umbrella) will dry out clay (permitting cracks to develop), or
destroy membrane liners through the action of ultraviolet radiation; 5) Subsidence--an uneven cave-in of the cap
caused by settling of wastes or organic decay of wastes, or by loss of liquids from landfilled drums--can result in
cracks in clay or tears in membrane liners, or result in ponding on the surface, which can make a clay cap
mushy or can subject the cap to freeze-thaw pressures; (6) Rubber tires, which "float" upward in a landfill; and
(7) Human activities of many kinds.
47
Radon? You should care, says province
The invisible killer will claim about 50 Nova Scotians' lives this year. But when a world-renowned
expert came to Halifax in October to hold a workshop on radon, hardly anyone showed up.
By Jamie Lee <[email protected]>
Posted: Nov. 5, 2007




Health Canada lowered their standard for acceptable radon levels in the home this year from 800
Becquerels per cubic metre to 200 Becquerels per cubic metre.
People who are in their basement regularly are more susceptible to high radon levels because the
gas seeps through cracks in the basement foundation.
Rocks known to contain radon are shale and granite. Sandstone and soil may also contain the gas.
Testing has been done in schools and hospitals. One office in Atlantic Memorial Consolidated
School in Whites Lake, NS, tested a wide range of radon levels last spring so it was closed down.
The surrounding rooms followed more testing.
The advisory committee on radon urges homeowners in Nova Scotia to test their houses for high radon
levels which could cause lung cancer after longtime exposure.
Just because you can't see or smell it, doesn't mean you can forget about it. Radon could be lurking in your
home and the province is pleading with Nova Scotians to take it seriously.
But its efforts haven't been catching on. The Department of Environment and Labour brought in Bill Angell,
a world-renowned expert on radon from Minnesota, to hold a six-day course in October on radon
measurement and mitigation at Dalhousie University. No media showed and the department is
disappointed.
Radon is the second-leading cause of lung cancer after smoking so the government wants people to test
the gas that seeps through a house's foundation. But few are aware of its harmful effects because it's
impossible to tell if someone has cancer specifically because of it.
Radon is an odourless, colourless gas – it’s invisible. Studies show it
comes from certain types of rocks like granite, but that doesn’t mean
they’re the only areas radon is found. Nova Scotia, unlike provinces like
Saskatchewan, isn’t known for particularly high levels of radon but because
the province has the rocks that emit radon, there is still a risk.
Dr. Louise Parker researches radon at the IWK Hospital in Halifax.
Dr. Louise Parker, an expert on environmental causes of cancer, says
radon is responsible for 15 per cent of lung cancer cases worldwide. That means radon makes up three per
cent of all cancers in the world.
Though approximately 80 per cent of lung cancer is from smoking, radon can also be a mutual cause for
the cancer. Smokers tend to be more susceptible to radon than non-smokers.
Patrick Wall, chair of the advisory committee on radon, adds that there will be an estimated 2,000 deaths
due to radon in Canada in 2007. About 50 of those cases will be in Nova Scotia.
Health Canada recently lowered the standard for acceptable radon levels by four times because it realized
people were actually more easily susceptible to the gas than previously thought.
The committee, made up of several provincial departments and cancer societies, announced the new
guidelines but did not start to campaign until fall. Spokesperson Brett Loney from the Department of Health
48
Protection and Promotion says it’s inaccurate to test in spring. When heating season starts, people close
their windows so the house isn’t ventilated properly, which means that radon becomes more concentrated.
The committee faces many challenges in their campaign. Loney says there are so many health messages
in the public that people have to decide what concerns them most. Because effects aren’t immediate,
radon-induced cancer isn’t a priority.
Parker agrees. “It’s like smoking – if you start smoking today, you’re not going to get lung cancer tomorrow.
But you may very well get it in 30 years’ time,” she says.
She adds people don’t realize radon’s danger because it’s impossible to pinpoint how radon affected an
individual’s health. It’s different with smoking, she says, because smokers know how much they smoked
through their life.
A radon test kit. The device must be active for at least 90 days for
accurate results. It can cost anywhere between $40 to $75.
Parker also says Nova Scotia’s efforts to raise awareness about radon
are new so there is little research to back up the campaigns. She
hopes homeowners start testing and notify the committee of the
results. “That will populate the radon map,” she says.
Since it’s too difficult to look back on an individual’s history of
exposure, says Parker, the committee is embarking on a study to
follow people for the next years to examine what affects someone’s susceptibility to radon-induced cancer.
Personal test kits for homeowners have to be ordered from suppliers and sent back for the results. The
device must be placed in an area of the house, preferably the basement, for at least 90 days.
Just because a neighbour is safe doesn’t mean it’s also safe next door, so it’s essential that every
homeowner does the test. It depends on the fractures in the basement’s floor and walls that are in contact
with the soil.
It does take a long time to get accurate results. “It’s sort of like collecting drips from a tap to judge how
much water was leaking – if you catch one drip it doesn’t give you a good idea,” says Parker. But the
homeowner doesn’t have to do anything.
There are a people, though few, who have been testing their homes since the committee started. Dean
Walker, owner of Atlantic Water Investigations Ltd., conducts radon testing for people looking to buy homes
in Halifax. He finds most of the people who want the test are from Europe or the U.S. where it’s already a
common practice.
A personal test kit can range anywhere from $40 to $75. Loney says the cost should not be a deterrent for
people. Homeowners should be used to these responsibilities. For example, he notes that homeowners
with wells and septic tanks have to test them regularly.
“As a homeowner you have to pay the price for it,” says Loney.
And once high radon levels are detected, it’s easy to rectify the problem by sealing cracks in the house’s
foundation.
49
What is soil degradation?
Soil degradation has two major components: the loss of
soil through erosion and the loss of soil fertility. Both
components lead to progressively lower crop yields,
increased costs of production, and may end up in land
abandonment and desertification. Soil tillage is the
principle cause of degradation of cropped fields. Soil
tillage causes rapid breakdown of soil organic matter the key to soil fertility.
What is a fertile soil?
A fertile soil allows the crop to produce close to the limit imposed by the environment (moisture and
adiation), provided that the crop management is optimal. Soil fertility has three equally important
components: soil chemical, physical and biological fertility. A reduction in any of the three components will
generally result in lower yields. Soil organic matter is the key to all three components of soil fertility –
reduced soil organic matter leads to less chemical, physical and biological fertility.
What is soil chemical fertility and how can it be maintained and improved?
Chemical soil fertility is the ability of a soil to provide all of the nutrients required by the crop. It is important
to remember that chemical fertility depends on the availability of nutrients in the soil – nutrients in
unavailable forms or in soil zones not accessible to roots do not help produce crops. The availability of
nutrients is normally greater when they are associated with organic matter. Soil chemical fertility can be
enhanced by applying manure, fertilizer, compost and lime.
What is physical soil fertility and how can it be maintained and improved?
Physical soil fertility is the ability of the soil to
enable the flow and storage of water and air into
the soil, to permit root growth and to anchor the
plants. To be fertile a soil needs abundant and
interconnected pore space. Pore space
generally depends on aggregates (crumbs) of
soil particles held together by soil organic
matter. Soil tillage breaks down aggregates,
decomposes soil organic matter, pulverizes the
soil, breaks pore continuity and forms hard pans
which restrict water and air movement and root
growth. On the soil
surface, the powdered soil is more prone to
sealing, crusting and erosion. Improving soil
physical fertility involves reducing soil tillage to a
minimum and increasing soil organic matter.
How can soil degradation be avoided?
The three biggest factors involved in soil degradation are a) soil tillage (breakdown of physical fertility); b)
removal of crop residues (mainly by grazing or burning), and c) nutrient mining (not applying manure,
compost or fertilizer in adequate amounts). The key therefore to avoid land and soil degradation is to
reduce soil tillage to a minimum, leave as many crop residues as possible, and replenish the nutrients
removed by the crops.
50
What are mine tailings?
Tailings are milled and finely crushed rock leftover after the process of separating the gold from the ore
bearing rock.
There are approximately 13.5 million tonnes of tailings stored in ponds constructed on the surface at the
Giant Mine site. The south, central, north and northwest tailings ponds cover a total of about 95 hectares. In
addition, water treatment sludge is stored in settling and polishing ponds covering an additional nine
hectares. Both the tailings and the sludge contain moderate amounts of arsenic. They are subject to wind
erosion when dry, and could also be directly taken up by animals looking for salt.
History of tailings at Giant Mine
The depositing of tailings on the surface of Giant Mine started in 1948 and continued until 1999. From 1948
to early 1951, a relatively small amount of tailings were deposited at the edge of north Yellowknife Bay on
Great Slave Lake. Subsequently, tailings were deposited directly into natural lakes, behind earth dikes, and
in the engineered tailings impoundments (forming the current north, central, south and northwest ponds on
the Giant property). Mill tailings were also placed in the underground mine as backfill in mined-out areas.
Water treatment sludge has been deposited over the tailings behind Dam 1 starting in approximately 1983,
and every summer since. A separation dike was constructed in the mid 1980s, resulting in the present day
configuration of separate settling and polishing ponds.
51
How will the tailings be remediated?
The Remediation Plan calls for the tailings and sludge areas to be covered with one layer of quarried rock
and a second layer of fine-grained soil. The lower layer of quarried rock will prevent the upwards migration
of contaminants from the tailings, and reduce the downwards penetration of plant roots. This layer will also
act as a physical and protective barrier against the removal of tailings by erosion.
The upper layer of fine-grained soil will allow for re-vegetation and future recreational or traditional uses of
the site. The surface of each tailings area will be graded, and ditches or spillways constructed to limit
erosion and allow water to run off the cover without becoming contaminated.
Why remediate the tailings?
The Giant Mine Remediation Plan calls for the remediation of the surface of the mine site to the industrial
standards set out in the Environmental Protection Act; with a specific focus on minimizing the release of
contaminants from the site to the surrounding environment. To meet this objective, the tailings and sludge
pond surfaces will need to be covered.
The specially-constructed cover will create a physical barrier between the tailings/sludge and people making
use of the remediated surface, prevent dust release and direct physical exposure to tailings, and prevent the
inadvertent exposure of plants, animals and people to the arsenic contained in the tailings and sludge.
The cover will also prevent: the contamination of clean surface water through direct contact with tailings;
surface water from wicking arsenic salts upwards; and vegetation from establishing roots in the tailings and
sludge.
Finally, the cover and its ditches or spillways will ensure clean surface water runoff and the establishment of
self-sustaining vegetation for aesthetic purposes.
What will the tailings ponds look like post-remediation?
The covered tailings areas will be re-vegetated to fit in with the surrounding landscape; however the ponds
will still be recognizable as they will be relatively flat with gentle drainage slopes. The remediated tailings
ponds may be available for various recreational uses – snowmobiling, hiking – once the vegetation has
become well established.
The GNWT's Department of Municipal and Community Affairs is examining options for future land use at
Giant Mine.
Will the remediated tailings ponds be safe?
Yes. The tailings and sludge covers will be inspected annually for five years or until vegetation is fully
established and erosion rates are found to be consistent with those naturally-occurring in the local
environment. Any run-off water from the tailings covers will be monitored to ensure that is not
contaminated.
How long will it take to remediate the tailings ponds?
The remediation of the surface of the Giant Mine site – including demolition and removal of more than 100
buildings – is expected to be completed within five years of the implementation of the Giant Mine
Remediation Plan.
The remediation of the sub-surface contamination using the Frozen Block Method is expected to take
considerably longer.
52
What issues are raised by tailings management?
The first issue is making sure that tailings storage areas are located properly. Extensive studies are done in
an effort to site tailings storage facilities away from sensitive environmental areas – such as lakes and
streams, wetlands, fishing, and hunting areas.
Secondly, care must be taken to ensure that tailings material is as environmentally friendly as possible.
This can be achieved by designing a milling process that captures the vast majority of minerals present in
ore, and by ensuring that the chemicals present in tailings are kept at predictable and manageable levels.
Finally, tailings storage areas must provide for the safe and permanent storage of tailings material. This is
achieved by designing tailings embankments to withstand any potential catastrophic event – such as an
earthquake or flood – and by controlling the seepage of tailings water.
53
54
ENVIRONMENTAL EFFECTS OF STRIP MINING
A
ll mining operations have a disruptive effect on the environment, but the sheer volume of material
involved in strip mining makes the impact on the environment especially acute. Surface mining (another
name for "strip mining") can severely erode the soil or reduce its fertility; pollute waters or drain
underground water reserves; scar or altar the landscape; damage roads, homes, and other structures; and
destroy wildlife. The dust and particles from mining roads, stockpiles, and lands disturbed by mining are a
significant source of air pollution. In order to participate effectively in controlling the abuses of strip
mining, it is important to understand the basic techniques of surface mining and the types of environmental
damage that can result.
The Mechanics of Strip Mining
This section describes the five main types of surface coal mining techniques: area mining, open pit mining,
contour mining, auger mining, and mountaintop removal. Underground mining is also considered in this
section. Terrain, economics, and custom generally dictate which technique an operator chooses.
All surface or strip mining first removes the overlying vegetation, soil and underground rock layers in order
to expose and extract coal from an underground seam or coal deposit. Responsible surface mining attempts
to limit the side effects of this removal through several basic steps:
1.
2.
3.
4.
5.
6.
7.
8.
First, the surface vegetation (trees, bushes, etc.) under which the coal seam lies is scalped or
removed.
Next, the operator removes the topsoil, usually by bulldozers or scrapers and loaders. The operator
either stockpiles the topsoil for later use or spreads it over an area that already has been mined.
The exposed overburden is then usually drilled and blasted, and removed by bulldozers, shovels,
bucketwheel excavators, or draglines, depending on the amount of overburden and the type of
mining.
After removing the overburden, the exposed coal seam is usually fractured by blasting.
The operator then loads the fractured coal onto trucks or conveyor belts and hauls it away.
Next, the operator dumps the overburden or spoil that was removed during the mining process on a
previously mined area and grades and compacts it. (Special handling may be necessary if any of the
overburden contains toxic materials, such as acid or alkaline producing materials.)
Any excess overburden that remains after the mined area is completely backfilled (Eastern mines
generally have substantial excess spoil) is deposited in a fill.
Finally, the operator redistributes the topsoil and seeds and revegetates the mined area.
While these basic steps are relatively consistent, the environmental impacts of the five main techniques vary
significantly.
Area Mining
Area mining is the technique most often employed in the flat or gently rolling countryside of the Midwest
and western United States. Area mines excavate large rectangular pits, developed in a series of parallel
strips or cuts which may extend several hundred yards in width and more than a mile in length. Following
scalping of the vegetation and topsoil removal, area mining begins with an initial rectangular cut (called the
box cut).
55
Area strip mining with concurrent reclamation.
The operator places spoil from the box cut on the side away
from the direction in which mining will progress. In large
mines, huge stripping shovels or draglines remove the
overburden. After extracting the coal from the first cut, the
operator makes a second, parallel cut. The operator places the
overburden from the second cut into the trench created by the
first cut and grades and compacts the spoil. The backfilled pit
is then covered with topsoil and seeded. This process
continues along parallel strips of land so long as the ratio between the overburden and the coal seam, called
the stripping ratio, makes it economically feasible to recover coal. Mining may cease in a particular area,
for example, where the coal seam becomes thinner or where the seam dips further below the surface.
When the operator reaches the last cut, the only spoil remaining to fill this cut is the overburden from the
initial or box cut. Yet, since the box cut spoil may lie several miles from the last cut, the operator generally
finds it cheaper not to truck the box cut spoil to the last cut. Instead, he may decide to establish a permanent
water impoundment in the last cut. These last cut lakes are commonplace in the coal regions of the Midwest
but may pose environmental and land use problems. A later section of this handbook describes strategies for
challenging these last cut lakes.
Open Pit Mining
Open pit mining is similar to area mining. The technique is common in the western United States (and other
parts of the world) where very thick — 50 to 100 foot — coal seams exist. Open pit mines are usually large
operations. Production levels may exceed 10 million tons of coal per year.
The thick coal seams found at these large mines ensure that the amount of land disturbed for each ton of
coal produced is much smaller than for most Eastern and Midwestern mines. Nonetheless, the sheer size and
capacity of these mines necessitates substantial surface disturbance. In open pit mining, the operator first
removes the overburden to uncover the coal seam. The overburden may be placed on adjacent, undisturbed
land, or it may be transported by belt or rail to the other end of the same mine or to an exhausted mine that
needs to be backfilled. Typically, several different pits, at various stages of development or reclamation, are
being worked at any given time on a single site.
Typical open pit mining method with thick coal seam.
Large machines remove the overburden in successive
layers until the coal seam is reached. The operator
then extracts the coal and transports it to a power
plant or to a rail line for shipment to a power plant.
Next, the operator backfills the pit with previously
extracted overburden and grades it. Topsoil that either
has been saved or transported from the ongoing
operation is spread over the spoil, and the area is
seeded.
56
The thin overburden and thick coal seams that are frequently encountered with open pit mines may result in
insufficient spoil material to reclaim the mined land. SMCRA provides an exemption from the
"approximate original contour" or AOC requirement for operators confronting this situation.[1]
Environmental Effects
Unless proper precautions are taken, any of these mining techniques will significantly harm the
environment. The older mining areas of Appalachia testify daily to this reality. In Appalachia alone,
thousands of square miles of mountainous terrain have been scarred by strip mining and left unreclaimed.
For 25 years, operators simply pushed overburden downslope from the mountain mines, causing landslides,
erosion, sedimentation, and flooding. The remaining unstable highwalls, often 100 feet high, crumble and
erode, disrupting drainage patterns and causing massive water pollution.
Erosion increases dramatically when the protective plant cover is removed and the remaining soil is not
stabilized. Studies show that water flows from selected mines carry sediment loads up to 1,000 times greater
than flows from unmined areas.[14] In a 1979 analysis, the Department of the Interior found gullies
greater than one foot in depth on more than 400,000 acres of mined land.[15] High sediment loads
and erosion also increase the likelihood and severity of floods, fill lakes and ponds, degrade water supplies, increase water
treatment costs, and adversely affect the breeding and feeding of certain fish.
Not all strip mining damage is as dramatic as mutilated mountainsides with highwalls exceeding 100
feet. SMCRA has helped eliminate many of these more obvious abuses. But long-term damage to the soil,
water and wildlife continues despite Congress' efforts to control it.
Damage to Land Resources
Long-term damage to soil resources from strip mining may be masked when intensive, short-term land
management gives a false impression that reclamation has been successful. Strip mining eliminates existing
vegetation and alters the soil profile, or the natural soil layers. Mining disturbs and may even destroy the
beneficial micro-organisms in the topsoil. Soil also may be damaged if reclamation operations mix the
topsoil with subsoils, diluting matter in the surface soil.
Strip mining also may degrade the productive capacity of adjacent land. Spoil placed on adjacent land that
has not been properly prepared may erode and thereby cover topsoil or introduce toxic materials to the soil.
Mining also may alter the natural topography of the area in ways that prevent a return to the previous land
use, such as farming. Returning the soil from the mined area to full productivity is especially important in
the Midwest, where some of the world's most prime farmland is now being mined for the coal that lies
beneath it.
In the western United States the arid or semiarid conditions of that region may increase the damage to soils
caused by mining. Once the natural vegetation is removed, erosion may increase dramatically. One of the
most persistent problems at western mines is establishing a "diverse, effective, and permanent vegetative
cover... capable of self-regeneration and plant succession at least equal...to the natural vegetation of the
area,"[16] Native vegetation in the West has adapted to the arid climate to provide maximum soil stability
during drought periods. Moreover, diverse native species provide forage for animals throughout the year.
But because revegetation using native species is often difficult and expensive, many operators choose nonnative species, which stabilize the soil over the short-term. Often, however, these species are not suited for
forage and they may not be capable of long-term self-regeneration as required by SMCRA.
57
Water Resource Damage
Irresponsible strip mining can pollute streams and disrupt water supplies. SMCRA was intended to prevent
these problems. Sometimes water pollution is easy to spot. Clear water often turns reddish-orange if it
contains a high concentration of iron. However, other types of pollution are harder to detect. A highly acidic
stream may look no different than a clean one unless you notice that it has no fish in it.
Water discharged from strip or underground mines must meet pollution standards for four major pollutants:
pH, iron (inapplicable during rainstorms and during the reclamation phase), manganese and suspended
solids (i.e., sediment). Let's briefly look at each of the major pollutants and problems they cause:
• pH — pH is a measure of the relative acidity of liquids. A pH of 7 is considered neutral. Liquid with a
pH below 7 is acidic; liquid with a pH above 7 is alkaline. Each number on the pH scale represents a 10fold increase or decrease in acidity. Thus, a pH of 3 describes a liquid that is 10 times as acidic as a
liquid with a pH of 4.[17]
The law requires that the pH of water released from a mine be between 6 and 9.[18] Although the more
common problem associated with mining operations is acid drainage (low pH), alkaline drainage (high
pH) is less common but can also cause problems. Alkaline mine drainage or runoff is most common in
the West, where alkaline overburden may be exposed to water during mining. Acid drainage is typically
caused when pyrite (fool's gold) or marcasite in the overburden is exposed to air and water during the
mining process. Rainwater mixes with the pyrite to form sulfuric acid which is washed into streams and
ponds below the mine.
Acid is one of the most damaging pollutants. It kills fish and other aquatic life, eats away metal
structures, destroys concrete, increases the cost of water treatment for power plants and municipal water
supplies, and renders water unfit for recreational use. Acid also may leach-out highly toxic metals or
cause them to be released from soils. These toxic substances kill aquatic life and can contaminate water
supplies causing serious adverse human health effects. Thousands upon thousands of miles of streams
have been degraded by acid mine drainage and runoff. Exposed acid material may continue to leach acid
for 800 to 3,000 years.



Iron— (Iron hydroxide, sometimes called "yellow boy") Increased amounts of iron in streams which
result from mining activity can be toxic to aquatic life and contribute to the "hardness" of water.
Manganese[19] — Manganese is a metal that is soluble in acid once it has been unearthed by
mining activity. It pollutes water supplies and corrodes other metals.
Suspended solids[20] — Also referred to as “TSS” (Total Suspended Solids) or sediment,
suspended solids are solid material, both mineral and organic, that has been moved from its place of
origin by air, water, ice, or gravity. Removing vegetation, blasting the overburden and using heavy
equipment create erosion and introduce sediment into streams. Sediment loads are particularly high
in mountainous and hilly terrains. Suspended solids reduce light penetration in water and alter a
waterway's temperature. Fish production is hindered; spawning grounds are destroyed. Sediment
increases the burden on treatment plants, and streams filled with sediment lose some of their
capacity to carry runoff following storms, thus making the stream more prone to flooding. A
sediment-laden stream flow can fill up a reservoir and severely reduce its useful life span. Finally,
sediment may act as a carrier for other pollutants such as pesticides, heavy metals and bacteria.
A mining operation that discharges or deposits overburden or spoil into a body of water, including streams
and wetlands, must obtain a permit under section 404 of the Clean Water Act (CWA). Section 404 regulates
58
any discharge of any dredged or fill material, including overburden from mining activities as well as
material deposited in a water body for construction purposes. A permit under SMCRA does not release a
mining operation from the obligation to obtain a CWA section 404 permit.
Section 404 applies to all “navigable waters” in the United States, which until recently the Army Corps of
Engineers (“COE”) has defined to include almost any river, lake, stream, pond, wetland, or other body of
water, including some streams that may not flow year round.[21] Section 404 requires that the mining
operator provide alternative proposals evaluating the discharge effects of overburden disposal on different
streams within the permit boundary.[22] It also requires that the discharge of fill does not jeopardize
threatened or endangered species, [23] does not violate state or federal water quality standards,[24] and does
not contribute to the significant degradation of waters of the United States.[25] Clean Water Act permit
requirements are discussed further in Chapter 5.
Mining activity can also affect the quantity and quality of groundwater supplies. In many coal fields, the
coal beds themselves serve as aquifers — underground supplies of water. The water in these aquifers flows
— although when compared to surface water streams, groundwater flows at a very slow rate. The fact that
groundwater flows, however, allows it to recharge or replenish many surface water systems. Surface mining
operations will necessarily cut through the coal aquifer and also any aquifer above the coal seam that is
being mined. Blasting activity and subsidence from underground mining may break up the impermeable
layers of rock that hold water in these aquifers, even where the overburden is not being extracted.
These aquifers may be the source of water for many wells. Flow patterns in such aquifers may be changed,
thereby adversely affecting water pressure in wells. Portions of aquifers and surface systems may be
dewatered, reducing the availability of water for other uses, and perhaps interfering with prior existing water
rights. Even where water losses from existing aquifers do not affect other users, disposal of excess water
from those aquifers may cause environmental damage.
It has yet to be demonstrated that a groundwater system destroyed by mining can be permanently
restructured. If not conducted properly, coal development — especially in the West — may leave behind
barren landscapes vulnerable to continual erosion and disrupted groundwater systems. As a result, the value
of these areas for agriculture and other uses may be greatly diminished.
Wildlife Damage
Wildlife often suffers severely as a result of strip mining. In the short term, all species are either destroyed
or displaced from the area of the mine itself. Mining also may have adverse, long-term impacts on wildlife,
including impairment of its habitat or native environment. Many animal species cannot adjust to the changes
brought on by the land disturbance involved in coal mining. In cases where an important habitat (such as a
primary breeding ground) is destroyed, the species may be eliminated. Unique habitats like cliffs, caves, and
old-growth forests may be impossible to restore.[26] Larger mines, such as those in the West, may disrupt
migration routes and critical winter range for large game animals.
As previously noted, strip mining exposes heavy metals and compounds that can alter the pH or acid
balance of runoff and leach into streams. Such pollution can impair the habitat of fish and other aquatic
species, thereby reducing population levels. Even where species survive, toxic materials can lower
reproduction and growth rates. Strip mining also causes increased turbidity and siltation of streams and
ponds, greater variation in stream flow levels and water temperature, and stream dewatering, all of which
contribute to the endangerment of aquatic species.[27]
59
When fill material is replaced following a strip mining operation, it is heavily compacted to prevent it from
eroding or sliding. As a result, easily-planted grasses out-compete tree seedlings, whose growth is slowed by
the compacted soil, and complete reforestation is unlikely. More effective reclamation techniques now exist
and must be promoted.[28]
What is land subsidence?
Land subsidence is sinking of the land surface. The elevation
of the land surface is lowered by compressing the many
layers of clay beneath the land surface. In the greater
Houston area, land subsidence is caused by the withdrawal of
groundwater. When we pump large amounts of groundwater
from the aquifers beneath us, we pull water out of the many
layers of clay, which allows the clay to compact under the weight of everything above them. In other parts
of the world, other things can cause subsidence besides the pumping of groundwater, such as oil and gas
withdrawals and even coal mining. Some natural land subsidence occurs over long periods of time, due to
the natural settling of sediments left over from millions of years ago, but nothing compared to the rates of
subsidence caused by us.
What harm is there in subsidence?
In the low elevation areas, generally nearest the coast, land
subsidence from 1906 to current of as much as 10 feet has
been recorded (Map of Subsidence 1906-2000). When the
elevation of your house is only 10 feet above sea-level and
you lose 10 feet of elevation because of subsidence, your
house is now under water. The Brownwood Subdivision in
the City of Baytown is a perfect example of the effects of
subsidence in coastal areas. Brownwood is now mostly underwater and has been turned into a nature center
by the City of Baytown. Further inland, subsidence is not as evident because the relationship to sea-level is
not as apparent, but still of great concern. The land surface of the greater Houston area is very flat and
therefore prone to flooding. We also get a lot of rain in the average year, and sometimes a lot of rain when a
tropical storm or hurricane moves through. Flooding has always been a major issue in the area. By
continuing to over pump groundwater, we potentially change drainage patterns of creeks and bayous,
increasing flow into some areas and decreasing flow out of those areas. From 1978 to 2000, as much as 5
feet of subsidence has been measured in northwest Harris County (Map of Subsidence 1978-2000).
How can subsidence be stopped?
Very simply put, subsidence will be stopped when we quit pumping too much groundwater. However, the
conversion from groundwater to alternative sources of water (surface water, treated effluent, etc.) is not as
simple. Many of the cities, industries, and others in the coastal areas converted years ago to surface water, at
considerable costs. The area has considerable supplies of surface water, through the development of Lake
Livingston on the Trinity River, Lake Houston and Lake Conroe on the San Jacinto River, and the Brazos
River.
60
Groundwater Contamination
What kind of contamination is it?
Groundwater is rain water or water from surface water bodies, like lakes or streams, that soaks into the soil and
bedrock and is stored underground in the tiny spaces between rocks and particles of soil. Groundwater pollution
occurs when hazardous substances come into contact and dissolve in the water that has soaked into the soil.
How did it get there?
Groundwater can become contaminated in many ways. If rain water or surface water comes into contact with
contaminated soil while seeping into the ground, it can become polluted and can carry the pollution from the soil to
the groundwater. Groundwater can also become contaminated when liquid hazardous substances themselves soak
down through the soil or rock into the groundwater. Some liquid hazardous substances do not mix with the
groundwater but remain pooled within the soil or bedrock. These pooled substances can act as long-term sources of
groundwater contamination as the groundwater flows through the soil or rock and comes into contact with them.
How does it hurt animals, plants or humans?
Contaminated groundwater can hurt animals, plants, or humans only if it is first removed from the ground by
manmade or natural processes. In many parts of the world, groundwater is pumped out of the ground so it can be
used as a source of water for drinking, bathing, other household uses, agriculture, and industry. In addition,
groundwater can reach the surface through natural pathways such as springs. Contaminated groundwater can affect
the quality of drinking and other types of water supplies when it reaches the surface. Contaminated groundwater can
affect the health of animals and humans when they drink or bathe in water contaminated by the groundwater or when
they eat organisms that have themselves been affected by groundwater contamination.
How can we clean it up?
Different approaches are used to clean up contaminated groundwater. Sometimes polluted groundwater is pumped
from the soil or bedrock, treated to remove the contamination, and then pumped back into the ground. If
contaminants are released into the groundwater slowly, large amounts of groundwater need to be pumped to remove a
relatively small amount of contamination. In this case groundwater contamination is addressed by containing the
contamination in a limited area to keep it from harming animals and plants. Still other types of contamination can be
left in the ground without active pumping and treatment. In these cases, contaminants are reduced to non-toxic
concentrations by natural biological, chemical, and physical processes before the contamination reaches the surface.
Sources of groundwater contamination
There are many different sources of groundwater contamination. Groundwater becomes contaminated when
anthropogenic, or people-created, substances are dissolved or mixed in waters recharging the aquifer.
Examples of this are road salt, petroleum products leaking from underground storage tanks, nitrates from the
overuse of chemical fertilizers or manure on farmland, excessive applications of chemical pesticides,
leaching of fluids from landfills and dumpsites, and accidental spills.
Contamination also results from an overabundance of naturally occurring iron, sulphides, manganese, and
substances such as arsenic. Excess iron and manganese are the most common natural contaminants. Another
form of contamination results from the radioactive decay of uranium in bedrock, which creates the
61
radioactive gas radon. Methane and other gases sometimes cause problems. Seawater can also seep into
groundwater and is a common problem in coastal areas. It is referred to as "saltwater intrusion".
These contaminants can originate from a “point source” or “non-point source” – meaning they can come
from a single source (or point) or, that they don’t have one specific source and come instead from the
cumulative effect of any number of factors or activities.
Below are some of the many point- and non-point sources of groundwater pollution, as well as more
detailed explanations of four of these contaminants: septic disposal systems, saltwater intrusion, leaking
underground storage tanks and DNAPLs.
Point sources



















On-site septic systems
Leaky tanks or pipelines containing petroleum products
Leaks or spills of industrial chemicals at manufacturing facilities
Underground injection wells (industrial waste)
Municipal landfills
Livestock wastes
Leaky sewer lines
Chemicals used at wood preservation facilities
Mill tailings in mining areas
Fly ash from coal-fired power plants
Sludge disposal areas at petroleum refineries
Land spreading of sewage or sewage sludge
Graveyards
Road salt storage areas
Wells for disposal of liquid wastes
Runoff of salt and other chemicals from roads and highways
Spills related to highway or railway accidents
Coal tar at old coal gasification sites
Asphalt production and equipment cleaning sites
Non-point (distributed) sources



Fertilizers on agricultural land
Pesticides on agricultural land and forests
Contaminants in rain, snow, and dry atmospheric fallout
62
Hazardous Wastes
ARTICLE CONTENTS: Disposal Problems | Treatments | Radioactive Wastes | Hazardous Waste Management | Marine Environment | Governance | Links to Other Sites
Waste may be defined as any substance for which the generator or owner has no further use. Hazardous wastes are waste substances whose disposal in the
environment could potentially pose hazards to human health, jeopardize natural or agricultural resources, or interfere with other amenities. Disposal of
hazardous wastes should be carried out in such a manner that the associated threats to people, resources and amenities are acceptable and minimal.
A recent environmental policy development, both internationally and within Canada, has been the formal acceptance of a concept known as the precautionary
approach (or principle). This embodies the ethic, long used by scientists in assessing potential dangers and risks, of adopting pessimistic assumptions in
assessments of environmental impacts and the formulation of environmental policy as a means of ensuring greater protection of the environment.
Terrestrial Environment
In the 19th century it was realized that WASTE DISPOSAL must take place in a well-regulated and safe manner, if only to control the spread of disease. The
ever-increasing variety of consumer goods generates wastes that are becoming increasingly hazardous. It has been estimated that a million people produce
50 000 to 250 000 t of hazardous wastes each year.
Disposal Problems
Standard sanitary landfills and sewage treatment facilities are inadequate for the disposal of many hazardous wastes, particularly those derived from industrial
practices. The dumping of untreated hazardous chemicals can have far-reaching effects. The discharge of inadequately treated liquid waste to rivers and
streams has created problems for communities downstream, and landfill dumps of waste chemicals have created significant health hazards to people living in
their vicinity.
Buried chemicals can produce vapours which can escape to the atmosphere, while liquids, if inadequately contained, can seep into the earth, enter
GROUNDWATER and affect drinking water supplies far from the dumpsite. Furthermore, a variety of products and degradation products remain in the
environment to enter the hydrologic cycle and be transported through it.
The insidious nature of the effects of low levels of some chemicals in the environment makes it difficult to set safe levels of human exposure. The effects of
carcinogenic and mutagenic chemicals may not show up for many years, and often the health defects that do occur cannot be related to a specific cause.
Treatments
Many hazardous wastes can be treated to render them relatively harmless to humans or to the environment. Such treatments include recycling, physical or
chemical reactions, incineration (high-temperature degradation), biological degradation, solidification, deep emplacement and long-term recoverable storage.
Recycling, by far the preferred method for recoverable chemicals (eg, waste oil, solvents), provides viable industries in many countries, including Canada.
Some chemicals can be treated chemically to form stable, nontoxic materials; eg, some acids can be neutralized to less hazardous brine or precipitated as
insoluble salts which can be landfilled.
Organic chemical wastes can be incinerated in properly designed furnaces equipped with scrubbers so that only carbon dioxide and water vapour reach the air
in appreciable quantities. Thus, even persistent chemicals such as polychlorinated biphenyls (see PCBs) can be safely destroyed in well-regulated installations
if the incineration time and temperature are sufficient for total decomposition and if adequate checks are made on the formation and emission of recombinant
products. Other hazardous chemicals normally emitted from chimneys (eg, fly-ash, other fine particles, acids and alkalis) can be electrostatically precipitated
or scrubbed out.
Many industries treat biodegradable liquid wastes with bacteria before discharge to surface waters. Heavy metal wastes (eg, electroplating liquors) can be
incorporated into a concretelike mass which resists leaching from burial sites. In some areas, waste liquids (eg, brine) can be ejected into permeable
underground formations overlain by impermeable rock (deep-well injection).
There is a distinct worldwide shortage of proper hazardous waste treatment facilities. In Canada, a milestone was reached 11 September 1987 when North
America's first comprehensive integrated hazardous waste treatment facility was opened at Swan Hills, Alta, with the full support of the local people. It is a
state-of-the-art facility, capable of treating and safely disposing of most hazardous waste produced in the province. Other provinces are attempting to set up
additional facilities to handle the estimated 5.9 million t of hazardous waste generated in Canada each year.
63
Radioactive Wastes
No practical detoxification methods are yet available for some kinds of hazardous wastes such as radioactive material (although it can be incorporated into a
matrix such as glass to restrict its release to the environment). Low-level radioactive wastes can often be disposed of safely in shallow trenches on land or can
be dumped in the ocean with acceptable risks to human health.
High-level radioactive wastes such as spent fuel rods are not amenable to such disposal and can either be stored temporarily for future treatment (eg,
reprocessing for the recovery of fissionable plutonium) or placed in permanent underground repositories, as is likely to be the case for spent nuclear fuel from
Canadian reactors. Sites for such repositories must be selected with the utmost care, taking into account all potential pathways of leakage which might result
in human exposure and all potential disturbances to sites which might threaten their integrity, such as tectonic activity or inadvertent human activity.
Hazardous Waste Management
Although most wastes can be treated for safe disposal, many are not currently so treated (because of short-term economic considerations) where regulatory
requirements allow such discretions. The costs of proper waste treatment are seldom included in the costs of production unless this is a regulatory
requirement. However, unless such requirements are applied uniformly in an international context, countries introducing more stringent environmental
protection regulations may be placed at an economic disadvantage in export markets. Even where legislation to eliminate unsafe practices exists, illegal
disposal can still remain a problem. Increased attention to the enforcement of regulations is thus essential.
Precautionary Approach
A more comprehensive approach to hazardous waste management incorporates 3 distinct principles: justification of practices; limiting risks to human health
and the environment; and minimizing detriment to the extent reasonable in the context of socioeconomic circumstances. Justification requires that the
potential benefits of the potential production and use of some new substance are assessed against the detriments (eg, the risks to human health and the
likely scales and risks of environmental damage) in order to determine that there is an overall net benefit to be gained from investment in the industry. Safe
limits to the exposure of humans to the products and wastes disseminated from the industry need to be established and regulatory action adopted to ensure
that releases of hazardous materials to the environment do not violate these limits irrespective of the route of exposure. Finally, all alternative options for the
production, transport, dissemination and disposal of hazardous products and wastes should be evaluated to ensure the selection of those that minimize the
exposures to the extent commensurate with technical, economic and sociopolitical conditions. In the field of radiation protection these 3 principles are applied
to practices and are referred to respectively as justification, compliance with dose limits and optimization.
Banned Substances
The current trend towards the adoption of greater precaution has resulted in moves to reach an international agreement to ban, or phase out, the production
of certain classes of substances such as some described as "persistent organic substances." These are substances determined to have the attributes of
toxicity, persistence and the potential to bioaccumulate. Many countries have already banned the production of DDT and PCBs, but the number of substances
so banned can be expected to increase if the contemporary trend in international negotiations continues.
Marine Environment
Various views are held on the use of the ocean as a receptacle for wastes. Some regard the ocean as "waste space" that could be used for waste disposal
because of its extensive capacity to assimilate materials without deleterious effects. Others feel strongly that the ocean environment should be preserved in
as pristine a state as possible because any major disturbance of the vast and complex oceanic ECOSYSTEM will be difficult to reverse. The former view reflects
the historical situation when the global population and urban communities were smaller and scale of anthropogenic activities (ie, produced by humans) was
much less than that of today. The latter view is now becoming dominant and is consistent with the increased adoption of the precautionary ethic.
Disposal Problems
The oceans have long been used, both deliberately and accidentally, for the disposal of human and industrial wastes. Potentially deleterious effects of
hazardous wastes disposed of into the marine environment include hazards to human health (eg, exposure of bathers to pathogens), hindrance with
legitimate uses of the sea (eg, fishing), degradation of the quality of sea water, making it less suitable for recreation, desalination or other uses, and less
tangible reductions in the aesthetic attractiveness of the ocean environment.
64
Contamination Sources
The main types of deliberate waste disposal into the ocean include direct discharge from land through outfalls or other pipelines, dumping from ships and
other marine platforms, and incineration on, or liquid discharges from, ships or marine and coastal platforms. Waste materials discharged on land or into
freshwater reservoirs (rivers and lakes) may also reach the sea, indirectly through land runoff.
Wastes routinely discharged by pipeline or outfall into the coastal zone in Canada include sewage and wastes from metal and oil refining, foodstuff processing,
and pulp and paper production. In Canada and other coastal states, heat is also discharged to the sea in cooling water from power utilities and from other
industrial facilities.
Another avenue for the introduction of waste materials found in the ocean is the atmosphere. Volatile substances, or substances with significant vapour
pressures, derived from terrestrial activities can enter the atmosphere and be subjected to short- or long-distance transport, frequently resulting in largescale contamination of land and ocean environments. An example of such large-scale contamination is that which occurred during the era of atmospheric
nuclear weapons testing in the 1950s and 1960s. More recent concerns have centered around the long-distance transport of relatively volatile organic
compounds that as a result of a global "distillation" process have a tendency to accumulate in cold regions such as the Arctic.
65