Download File

Geology (Continued from Study Guide part 1)
What are faults and where do you find them? A fault is a fracture in a volume of rock, where there has been
significant change in the original position (displacement) as a result of earth movement. They are the result of plate
tectonic forces. Energy release associated with rapid movement on active faults is the cause of most earthquakes.
There are three types of faults:



normal fault, the block above the fault moves down relative to the block below the fault. This fault motion
is caused by tensional forces and results in extension.
reverse fault, the block above the fault moves up relative to the block below the fault. This fault motion is
caused by compressional forces and results in shortening.
strike-slip fault, the movement of blocks along a fault is horizontal. The fault motion of a strike-slip fault
is caused by shearing forces (transform plate boundaries are types of strike slip faults.
Fault type animation - http://www.iris.edu/hq/programs/education_and_outreach/animations/2
What is soil composed of, and how is it made? Soil is a combination of mineral & organic matter, water & air that
supports plant life. It’s made from weathered rocks. It is classifies based on proportions of 3 different particle sizes:
–
Clay
–
Silt
–
Sand
What is weathering and what are the different types?
rock at or near the earth’s surface. There are 2 types:
Weathering - The disintegration and decomposition of
•
Mechanical - Physical forces break rock into smaller pieces without changing the composition of the rock.
•
Chemical - breakdown of rock by chemical means . Water usually introduces dissolved chemicals through
fractures, causing rocks to crumble or loosening thin pieces of material.
What factors affect the rate of weathering in rocks?
•
Temperature controls freezing and thawing and thermal expansion (increasing size, caused by heat).
Temperature also determines the rates of chemical weathering. An increase in temperature causes an
increase in the rate of a chemical reaction. So, weathering is faster in warm, moist tropical environments.
•
Climate has such a big impact on weathering that a geologist (Peltier) created a special formula to
determine the rate of weathering using only the annual temperature and rainfall of a place.
•
The mineral composition and structure of rock influences weathering. Some rocks (like limestone and
granite) are very susceptible to weathering because of their mineral composition they wear away easily.
•
Topography (the lay of the land) may affect weathering. On a steep slope landslides can exposure bare
rock which then becomes susceptible to weathering.
•
In the presence of vegetation the growth of plant roots wedges rock apart, increasing rates of weathering.
•
Humans increase weathering by pollutanting the atmosphere, increasing carbon dioxide, suluphur dioxide
and nitrogen oxide causing acid rain, which weathers rocks. Removal of vegetation by humans through
deforestation has resulted in a decrease in weathering .
What is erosion and what are the types? How does erosion effect various landforms? Erosion is the gradual
wearing away of land surface materials, especially rocks, sediments, and soils, by the action of water, wind, or a
glacier. It usually involves the transport of eroded material from one place to another (from the upstream, to the
downstream portion of a river).
Types of Erosion:
1.
2.
3.
4.
5.
6.
Erosion due to gravity - movement of sediment, rock, etc. down-slope from an area of higher elevation to
an area of lower elevation due to the force of gravity.
As a glacier (large chunks of ice) moves differences in pressure and melting/refreezing ice within the
glacier breaks pieces off and incorporate them into the glacier (plucking). Thrusting occurs when rock is
frozen to the bottom of the glacier. And is thrust forward with the glacier and then deposited elsewhere.
Glaciers also cause abrasion. As the glacier moves over the underlying rock with the pieces it has picked
up, it gouges, carves, and grinds up the underlying rock.
Whether or not wind erodes sediment depends on the size of the material, the velocity (speed) of the wind,
the duration of the wind, and the length of the area over which it can blow unobstructed. Smaller particles,
(grains of silt or clay) may be carried great distances before being deposited. Larger-sized particles move
by rolling or bouncing along the ground.
Along coasts, erosion is due to the wave action of water. Waves come is, sediment is disturbed and
pushed toward the beach. As waves flow back out, some sediment and sand flows back out. Sediment is
forever moving and rearranging. On rocky shores pressure from the impact breaks off small pieces of rock
that are carried back out into the water. The pieces collide further breaking them into smaller pieces.
Rainfall causes erosion everywhere, on farm and cropland the impact of raindrops on bare soil can
dislodge individual grains and break apart soil aggregates (clumps of soil particles held together by plant
roots, clay, etc.)
Rivers and streams erode and transport sediment by entrainment (lifting and carrying loose particles)
and dissolution (the process by which soluble materials are dissolved by the water and then carried along in
solution).
The total sediment carried by a stream is referred to as load and there are three types:
1.
2.
3.
dissolved load - material which is transported in solution
suspended load - material which is carried along in the water without settling to the bottom
bed load - material too large to be carried in suspension, it bounces or rolls along without being lifted
causing more erosion.
What are geohazards and how can you predict and prepare for them? Geohazards are rare geological
occurrences that endanger lives, property, and communities. They include events such as landslides, tsunamis,
flooding, earthquakes, avalanches, and volcanoes. They can even be caused by human activities. They cannot be
prevented but their impact may be lessened. To determine the probability of one of these geologic events
community planners, as well as individual citizens should do their research. They should examine the geologic
history and maps of an area before building homes, structures, or communities. It is important to see if the area has
a history of seismic activity (earthquakes), volcanic activity, flooding , is near a fault or plate boundary, has a
history of the ground that is unstable (from mining, adding or removing dirt, soil type etc.), is near the shore, etc.
Modern infrastructure should be designed to withstand probable local seismic events.
• Explain precautions that can be made to protect life from meteorological hazards. Some examples include
sinkholes, groundwater pollution, and flooding.
What are the consequences of human activities on the lithosphere?
•
•
•
•
•
Urbanization - Destroying natural areas can reduce the beauty of an area and have a potential economic
impact. Rapid development can result in very high levels of erosion and sedimentation in river channels.
Pollution of soils is possible by leaking gas tanks and other chemicals.
Deforestation is cutting down all the trees in an area loosens the soil and makes it very easy for extreme
erosion to occur. One solution is replanting and a system of harvesting that thins out the area.
Agriculture takes space. Use of chemical pesticides, insecticides and fertilizers can contaminate soil and affect
soil fertility. Organic fertilizers are better. Planting the same crop over and over can strip vital minerals out of
the soil. Crop rotation can help.
Overgrazing is the removal of excessive amounts of plant growth by animals in one area. This accelerates
erosion and strips away topsoil, resulting in no plants able to grow. Rotate animals among pastures.
Land Use - Solid household wastes that cannot be recycled are buried in landfills. If there are hazardous
chemicals that leak or heavy metals, it is possible that the soil can be contaminated even though the landfill is
lined.
What are the negative consequences of urbanization and deforestation, and why do we continue with these
practices if they are harmful?
Urbanization means to convert more rural areas into cities with a higher population, more factories, businesses,
subdivisions, malls, roads, vehicles, etc. These areas are created as people move to take advantage jobs, and to avoid
poverty in the rural area. People also move to the city is for convenience, everything you might want or need is all
there in one central location. The negative consequences of urbanization are pollution, destruction of plant and
animal habitat, erosion, acid rain, increased CO2 emissions which contributes to global warming and acid
precipitation, increased use and demand on natural resources, so many cars and factories in a smaller space creates
more concentrated pollution, and accumulation of more garbage which could cause health problems. It also
contributes to regional changes in climate (like heat islands in large cities like NY, Chicago, Beijing, etc). These are
caused by lack of vegetation. Buildings, roads, and other infrastructure replace open land and vegetation. Surfaces
that were once permeable, cool, and moist become impermeable, hot, and dry. These changes cause urban regions to
become warmer than their rural surroundings, forming an "island" of higher temperatures. Sustainable development
ideas to help with the issue of urbanization include encouraging the use of green building techniques and materials
in new construction and improvements, responsible practices such as water and energy efficiency improvement
(installing lower consumption equipments, LED lamps, solar water heaters, rainwater collection), use of sustainable
construction materials, waste management control in the building process (reusing demolition materials, among
other measures), household waste management and recycling, and reforestation of the surrounding environmentally
protected areas.
Deforestation means to completely destroy or cut down forests. Deforestation occurs for many reasons: trees are
cut down to be used or sold as fuel (sometimes in the form of charcoal) or timber, while cleared land is used
as pasture for livestock, and settlements. The removal of trees without sufficient reforestation has resulted in damage
to habitat, biodiversity loss and aridity (extreme dryness). It has adverse impacts on the capture of atmospheric
carbon dioxide by plants. A more sustainable way to use our forests would be to selectively cut certain trees, instead
of cutting down everything (clear-cutting).
What are artificial stabilization efforts? How are they used to combat human activity on our shorelines and
mountainsides? Human Activity and Shorelines - Removal of vegetation at the coast can cause serious erosion.
The plants help hold the sand in place. Man made erosion control, like sandbags, can make erosion worse
downshore. Erosion causes houses to be condemned and potentially fall into the ocean.
Mountainsides - Blasting away rock to build roads has destabilized many mountains. Building houses and other
structures, removing the tops of mountains for mining, and logging forests have all led to the need for stabilization
to prevent erosion on mountainsides.
Name some energy resources we utilize in North Carolina and discuss the effect of these activities on the
environment.
•
•
•
•
Mining - Underground mining for resources such as coal, requires digging out large areas, increasing the
risk for sinkholes and cave ins. Strip mining destroys the environment. Mine operators are required to
perform reclamation (putting the land back together in its original condition) after finishing with the mining
site.
Harvesting Peat - Peat is an accumulation of partially decayed vegetation. Eventually, peat can turn into
coal. Peat can be burned for fuel. The advantages are low sulphur content, minimal mercury content, low
ash content, energy values equivalent to coal, less expensive than oil and natural gas, and price competitive
with other biofuels, minor engineering retrofit needed when substituted for, or blended with, coal. Since
peat forms nearer to the surface, it requires less digging.
Drilling for Oil and Natural Gas - Oil and Natural Gas are nonrenewable resources that will eventually
run out. Drilling can cause the lithosphere to be disturbed. It can cause earthquakes. Soil and groundwater
can be contaminated. Fracking is a hot political topic.
Wood – Wood products are harvested from our forests or privately or commercially owned land. It can
destroy habitat and reduce species diversity. Traditional techniques involve clear-cutting, but a more
sustainable practice would be to selectively cut trees of a certain type or size and leave other trees for the
sake of biodiversity and ecosystem health.
What are the structures and processes within the hydrosphere? The water in Earth’s oceans, seas, lakes, rivers,
and glaciers, as well as the water underground and in the atmosphere make up the hydrosphere. Water can also be
classified according to where it is located. Groundwater is any water that travels or is stored under the ground.
Surface water is any water that travels, or is stored on top of the ground. This includes water that is found in rivers,
lakes, streams, reservoirs and the ocean.
The Water Cycle - Earth’s water supply is recycled from the hydrosphere to the atmosphere in a continuous process
called the water cycle, which is fueled by the Sun. In this cycle water changes from one state to another at the
temperature and pressure normally experienced at earth’s surface. The water cycle involves:
• Evaporation – liquid water becomes gaseous water. (i.e. water to water vapor)
• Depositon = when water vapor changes directly to a solid.
• Condensation – the water vapor cools and becomes a liquid again. (i.e. water vapor to dew or rain)
• Precipitation – this occurs when the water that has condensed in the clouds falls back to the Earth as rain,
sleet, hail or snow.
• Infiltration – this occurs when water soaks into the ground and becomes groundwater.
• Runoff – It can run across the ground until it reaches a lake, stream, river, reservoir or the ocean.
ATMOSPHERE
What is the composition and structure of our atmosphere? The atmosphere is composed of (in order from
largest component to smallest) Nitrogen, Oxygen, Argon, and Carbon Dioxide, and other gases. Air also contains a
variable amount of water vapor (around 1%). Understanding how water vapor interacts in the atmosphere is the
most important part of understanding weather. The atmosphere is composed of the following are the layers:
•
Exosphere (Top) - the uppermost edge of the atmosphere containing the lightest gases (hydrogen and
helium). There is no clear boundary between outer space and the Exosphere. It’s bounded underneath
•
Thermosphere - contains the Aurora (Northern Lights) which is a natural light display in the sky caused
by collisions of charged particles directed by the magnetic field. They only occur in the polar regions. It’s
bounded underneath by the Mesopause. hardly has any atmospheric particles in it. Also contains the
*Ionosphere – the portion of the upper atmosphere, from the mesosphere through the thermosphere, that
has ionized solar radiation. It is a shell of electrons and electrically charged atoms and molecules that
surrounds the Earth that is important for
•
Mesosphere - Is the layer of the atmosphere where meteors burn up.
•
Stratosphere - Is the layer of the atmosphere which has the maximum layer of ozone(O3).Transcontinental
planes fly here and some military air craft. Weather balloons go up to this altitude and some stratus clouds
are found in the lower layers of the Stratosphere.
•
Troposphere (Bottom) - Is the bottom-most layer of the atmosphere in which all weather occurs. It’s also
where most planes fly. Where most all of our clouds are and water vapor which means this is where
weather forms.
Temperature and Density
Warmer matter is less dense than colder matter, so warm air rises. Differences in temperature cause a flow of heat
from warmer matter into colder matter. Thermal Energy is the amount of kinetic energy (i.e. movement) in a
substance. The more energy that is added, the more excited the atoms becomes and the faster they move. Therefore,
when energy is transferred to air, for example from sunlight, the particles of air move faster.
What is an air mass? How do they form? What type of weather occurs when they meet? An air mass is an
immense body of air that is characterized by similar temperatures and amount of moisture at any given altitude.
When an air mass moves out of the region over which it is formed, it carries its temperature and moisture conditions
with it. As it moves, the characteristics of an air mass change and so does the weather in the area over which the air
mass moves. When two air masses meet, they form a front (boundary that separates two air masses.). Warm
fronts forms when warm air moves into an area formerly covered by cooler air. Cold fronts form when cold, dense
air moves into a region occupied by warmer air. Stationary fronts form when the surface position of the front does
not move. Occluded fronts form when an active cold front overtakes a warm front.
Air masses are characterized by temperature and surface over which they form. What are the types?
• Maritime polar: form over water in the polar regions – they are humid and cold (mP)
• Maritime tropical – form over water in the tropical regions – they are humid and warm (mT)
• Continental polar: form over land in the polar regions – they are dry and cool (cP)
• Continental tropical: form over land in the tropical regions – they are dry and hot (cT)
Much of the weather in North America, especially in weather east of the Rocky Mountains, is influenced by
continental polar and maritime tropical air masses.
How can you use weather maps and other data (surface, upper atmospheric winds, and satellite imagery) to
predict the weather? Weather forecasting involves a combination of computer models, observations, and a
knowledge of trends and patterns. By using these methods, reasonable accurate forecasts can be made up to seven
days in advance. The symbols shown on the left below are used to represent the factors that are considered when
making a weather prediction.
How do you use a relative humidity chart?
Use Table 11-1 (above on the right) to determine relative humidity. The numbers in the center of the chart represent
relative humidity in percentages. Relative humidity is determined by finding the differences in degrees between the
dry-bulb and wet-bulb readings on the horizontal scale at the top, and then reading off where this column intersects
the horizontal row containing the dry-bulb temperature reading. In this example, the dry-bulb temperature is 20 °C
and the wet-bulb temperature is 14 °C. The difference between the two readings (dry-bulb depression) is 6 °C.
According to the table, when the dry-bulb depression is 6 °C and the dry-bulb temperature is 20 °C, the relative
humidity is 51 percent.
Pressure , Temperature, and Measurement Tools
Isobars = show area of equal air pressure (when they are close together it is called a “steep pressure
gradient” and that means strong winds. When they are spaced apart then that indicates weak winds)
Isotherms = shows area if equal temperatures, but look like isobars.
Barometer = measures air pressure
Anemometer = measures wind speed.
Psychrometer = measures relative humidity (wet and dry-bulb thermometers can also be used)
What causes wind? Wind is caused by differences in air pressure that comes from differences in the temperature of
air that ultimately comes from how the atmosphere has been heated by solar radiation. So, to sum it up, winds are
caused by differences in air pressure between areas. The air pressure varies because the temperature varies. Warmer
air expands as its molecules spread far apart so it tends to weigh less and pressure is lower. The molecules in cold
air, however, press more tightly together which makes the air weigh more and thus exerts a higher pressure. The
molecules in air generally flow from areas of higher pressure to areas of lower pressure. This flow of air is what we
call wind.
What is a cyclone and an anticyclone? How do cyclonic storms form based on the interaction of air masses?
A cyclone is a storm or system of winds that rotates around a center of low atmospheric pressure. Winds in a
cyclone blow counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Cyclones
(commonly known as lows) generally are indicators of rain, clouds, and other forms of bad weather. In
cyclones, air close to the ground is forced inward toward the center of the cyclone, where pressure is lowest. It then
begins to rise upward, expanding and cooling in the process. This cooling increases the humidity of the rising air,
which results in cloudiness and high humidity in the cyclone. An anticyclone is a system of winds that rotates
around a center of high atmospheric pressure. Winds in an anticyclone blow the opposite of a cyclone. Winds
blow clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.
In anticyclones,
air at the center is forced away from the high pressure that occurs there. That air is replaced in the center by a
downward draft of air from higher altitudes. As this air moves downward, it is compressed and warmed. This
warming reduces the humidity of the descending air, which results in few clouds and low humidity in the
anticyclone. Anticyclones (commonly known as highs) are predictors of fair weather.
Why is water vapor important in terms of weather (clouds, relative humidity, dew point, precipitation)?
Water vapor is extremely important to weather and climate. Without it, there would be no clouds or rain or snow,
since all of these require water vapor in order to form. All of the water vapor that evaporates from the surface of the
Earth eventually returns as precipitation - rain or snow. When liquid water is evaporated to form water vapor, heat
is absorbed. This helps to cool the surface of the Earth. This "latent heat of condensation" is released again when the
water vapor condenses to form cloud water. This source of heat helps drive the updrafts in clouds and precipitation
systems, which then causes even more water vapor to condense into cloud, and more cloud water and ice to form
precipitation.
What safety precautions should be followed for severe weather and severe cyclonic storms (hurricanes) to
preserve life and property? No matter the type of severe weather, there are always three essential steps to disaster
and emergency preparedness: Have a disaster supply kit, so you're ready for any emergency, Develop a plan for
what you and your family will do before disaster strikes, Stay informed during severe weather... any way you can.
Hurricanes can change direction, speed and intensity quickly. Make a plan to protect the people and things you value
before a hurricane or tropical storm arrives. Board up windows and prepare for a potential evacuation. Below-
ground shelters, and reinforced "safe rooms" provide the best protection against tornadoes. Lightning is a threat
anywhere thunderstorms occur. If you hear thunder, it is time to take shelter.
What human activities negatively impact the atmosphere’s composition and how can we reduce these
impacts? Emissions from vehicles contribute the greatest amount of pollutants to the atmosphere. Stationary Fuel
Combustion (factories and businesses), Industrial Processes (making needed goods), and the Disposal of Waste also
contribute to air pollution. We can reduce our impact by using alternative fuel sources that will not harm the
environment (solar, wind, wave, geothermal). We could try not to creat as much waste by implementing the
“reduce, recycle, re-use” strategy. We could become more active in supporting legislation to ensure clean air, such
as the legislation that led to the ban on chlorofluorocarbons (CFC’s). These were chemicals that used to be in
aerosols (things like spray paint or hairspray) that were found to be damaging our ozone layer (our protective filter
from harmful UV rays). We could also try to use more natural products that don’t contain chemicals that could be
potentially harmful.
What does “reduce, reuse, recycle” mean? In order to conserve our resources and use less energy we could
implement the 3 R’s which are: Reduce. Purchase products that require less packaging or to limit the waste you are
producing. Reuse. Avoid single-use bottles, bags, kcups, etc. Recycle. Paper, plastic, glass, magazines, electronics,
and more can be processed into new products while using fewer natural resources and less energy.
The Hydrosphere: Water and its Interactions with Earth’s Spheres
How and why is sea-level changing? Sea levels are rising because we are adding greenhouse gases to the
atmosphere, and it is increasing temperatures, which are melting ice sheets in Greenland and Antarctica. As they
melt temperatures can increase further because less sunlight will be reflected from their surfaces back out into space.
Vocabulary
•
•
•
Sealevel - the horizontal plane corresponding to the surface of the sea at mean level between high and low
tide.
Shorelines are the line where shore and water meet.
Barrier Islands are relatively narrow strips of sand that are parallel to the mainland coast. They usually
occur in chains.
How will rising sea levels affect landforms such as shorelines and barrier islands? The shorelines would be
higher causing harm to coastal ecosystems like wetlands, which protect the shore from flooding, and provide
important habitats for many types of plants and animals. It could lead to inundation (covering land completely with
water), erosion, and saltwater intrusion (coming in) which increases the salinity of estuaries and aquifers threatening
water supplies and aquatic life. Storm surges would also be higher, and warmer temperatures (because less sunlight
is reflected to space) could increase the frequency and severity of hurricanes. With rising sea levels, barrier islands
could be created or destroyed. Storms can push sand landward onto the bay side of the island (it’s like rolling up a
rug - as the island rolls landward, it builds upward and remains above sea level). The other option is that the island
may break up, or become completely submerged and drown. Island disintegration appears to be more frequent in
areas with high rates of relative sea level rise.