Download Geosphere College notes

Higher Environmental Science:
The Geosphere
Dynamic Notes
Also available in large print (16pt)
and electronic format.
Ask Student Services for details.
www.perth.uhi.ac.uk
Perth College is a registered Scottish charity, number SC021209.
Recommended reading:



OCR Geology. Debbie Armstrong et al
CFC Higher Geography Course Notes
Blackboard Notes
Earth Resources
Course content: What you need to know
The Overview of Earth systems and their interactions underpins the key areas in this Unit
Interactions, including the cycles, among the geosphere, hydrosphere,
pedosphere, biosphere and atmosphere
Definition and classification of physical, biological, renewable and nonrenewable resources
Background reading for candidates attempting Higher Environmental Science without first
completing the National 5 course make sure you are aware of
 Rock cycle processes involved in igneous, sedimentary and metamorphic rock
formation
 Earth structure and history
 Mechanisms around plate tectonics
 Surface processes including cycle of erosion and types of weathering.
1


Geosphere
Mechanisms of destructive and construction plate boundaries, and their role in the
formation of named mineral deposits, including major mineral ores.
Plate movements(past and present) and the effect on resource distribution

Aluminium: formation, discovery, extraction, processing of aluminium ore and uses of
aluminium

Clay and baryite: formation, discovery, extraction and uses of baryite (oil drilling and
biomedical imaging) and clay (firebricks, bricks, tunnel and ditch support, ceramics,
fuller’s earth, cat litter, fining beer)

Shale oil and shale gas formation, discovery, extraction, processing and use
including the wider social issues relating to these

Sources of the Earth's internal heat, heat flow and geothermal power

Appraisal of the role of named legislation, and policies and initiatives for the
protection, promotion and sustainable use of the geosphere; policies to include
SSSI, Fossil Code, and Geoparks. Intrinsic value of the Earth’s surface, to include
tourism, recreation, quality of life measures.
.
.
.
.
TYPE REF HERE
1
Perth College UHI
Overview the Earth systems and their interactions
The earth is made up from four subsystems or spheres. These interact with each other to
form a connected system, called the Earth system
 Geosphere: all the rocks of the earth
 Pedosphere is used to recognise soils as a separate sphere
 Biosphere: all living things
 Atmosphere: all the gases surrounding the planet
 Hydrosphere: all earths water
Give examples of interactions between the different spheres associated with an erupting
volcano and a mixed farm in Perthshire
Interactions between the earth’s systems involve the movement of matter and energy at
different temporal and spatial scales. The rock, carbon, nitrogen and water cycles connect
the system
Perth College UHI
2
TYPE REF HERE
What is a resources?
A resource is the name of a material or the total amount of a material that can be
theoretically exploited. You need to be able to distinguish between different types of
resources. Classify the following resources found in the earth as physical, biological,
renewable, or non-renewable


Physical resources comes from the geosphere
A Biological resource has been defined as the living landscape, plants animals and
other aspects of nature that provide services
 Renewable resources: can be replenished
 Non-renewable resources: cannot be replenished in human timescales
Physical
Biological
Renewable
Non
Resources
Resources
renewable
Building stone
Limestone
Granite
Coal
Oil
Natural gas
Limestone
Copper
Nuts
Wind power
Nuclear power
Hydroelectric
power
Soil
Landscape
The structure of the earth
The earth is made up from layers: inner core, outer core, mantle and crust. Label the
diagram of the earth structure below. We will cover this in more detail when we look at plate
tectonics
What is the difference between a rock and mineral?
TYPE REF HERE
3
Perth College UHI
A rock is made up of one or more minerals.
A mineral is a substance that has a definite chemical composition.
e.g. Iron Pyrite: chemical formula FeS2 forms cubic crystals,
e.g. quartz SiO2 a framework of silicon tetrahedrons
The three main rock types
There are 3 main rock types - igneous, sedimentary and metamorphic.
1
Igneous rocks are formed from molten material (magma) that has cooled and
crystallised e.g., granite and gabbro.
2
Sedimentary rocks are formed from sands, silts, clays and other deposits laid down
on the Earth's surface which are then, buried and hardened e.g., sandstone and limestone.
3
Metamorphic rocks are formed by great heat and pressure on pre-existing rock
without causing it to melt e.g., schist and gneiss.
Perth College UHI
4
TYPE REF HERE
Activity:
formation
Sketch and label the key features of the three main rock types in terms of their
Igneous rock example e.g. granite
Sedimentary rock example e.g. sandstone
Metamorphic rock example e.g. gneiss
Visit the virtual interactive rock laboratory to see example of rock types found in Scotland
http://www.earthscienceeducation.com/virtual_rock_kit/DOUBLE%20CLICK%20TO%20ST
ART.htm
Mystery rocks
Identify the rock types and describe how they was formed
Sample 1
Sample 2
Sample 3
TYPE REF HERE
5
Perth College UHI
Perth College UHI
6
TYPE REF HERE
The Rock Cycle
Over geological time all rocks have probably been reconstituted several times. A granite
plateau like the cairngorms may be weathered and eroded to produce sands which in turn
may be transported and deposited in the sea. There the sands are buried and hardened to
form sandstone. Further burial metamorphoses the sandstone to produce gneiss. These
rocks may be buried even deeper and melt forming granite. Millions of years later earth
movements and erosion raise the granite to form mountains and the rock is once more
exposed to the ravages of weathering and erosion. This is known as the rock cycle.
Weathering is the wearing down of rocks: Physical, chemical biological
Erosion is the movement of broken pieces of rock from the site of weathering.
These sediments can be transported by rivers wind and ice and then deposited.
TYPE REF HERE
7
Perth College UHI
For example fast flowing rivers can transport large rocks, but slow moving rivers can only
transport tiny pieces of rock. Transport can also create more weathering as the sediments
bang into one another causing the particles to become more rounded
Complete the table of the processes and products of the rock cycle
Process
Products
Weathering( biological, physical and
chemical)
Erosion( and transport)
Layers of sediments
Burial and hardening(cementation) of
sediments
Metamorphic rocks
Melting to form magma
Rocks and mountains at the surface
Weathering video clip
http://www.bbc.co.uk/programmes/p011myd3
Plate Tectonics and the distribution and formation of minerals
What is plate tectonics? Visit the BBC Webpage below for a range of interactive materials
http://www.bbc.co.uk/science/earth/surface_and_interior/plate_tectonics
Activity: Write your definition of Plate Tectonics:
Research activity: Incorporate images into your notes
There are a number of excellent remote sensing images of the earth that clearly shows
evidence for plate tectonics, for example the mid-Atlantic ridge. Have an internet search
and see what you can find
Perth College UHI
8
TYPE REF HERE
The structure of the earth in relation to plate tectonics
Key words: Lithosphere, asthenosphere, oceanic crust, continental crust
http://www.tau.ac.il/~morris/03411203/chapter3/litho-astheno-sphere.htm
The Lithosphere is composed of the crust (oceanic and continental) and upper most layer
of mantle. This is the “plate” of plate tectonics. The lithosphere is rigid
The Asthenosphere is the part of the mantle that is capable of flow (over millions of years)
even although it is still solid. Partial melting of peridodite causes melted minerals to
surround each solid mineral allowing it to flow
Partial melting is when a proportion of the minerals will have a lower melting point allowing
them to melt while the rest remains solid
Questions
1. What is the difference between the crust and the lithosphere?
2. Where will the continental crust be thickest?
3. Explain how solid rock can undergo plastic flow
Continental drift is the large scale movement of continents. Evidence for this theory
comes from a number of sources.
Activity: Visit the website below and make a list of evidence for continental drift, insert
pictures and sketches of evidence in your notes
http://www.coolgeography.co.uk/Alevel/AQA/Year%2013/Plate%20Tectonics/Plate%20tectonics/Tectonics%20&%20Evidence.htm
Examples of local evidence that Scotland has drifted across the globe
 Coal formed in tropical environment
 Old red sandstone formed in desert environment
 Coral limestone formed in tropical ocean
TYPE REF HERE
9
Perth College UHI
Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust
is formed through volcanic activity and then gradually moves away from the ridge. One
source of evidence for seafloor spreading comes from magnetic anomalies:
Activity: Find evidence for seafloor spreading and add them to your notes
Continental drift applies only to the continental land masses. Sea floor spreading uses
evidence from the oceans. Both continental drift and seafloor spreading provide evidence
for plate tectonics.
Plate Movements
There are a number of processes involved in plate tectonic. The exact mechanisms are still
not certain. The plates move by a combination of “slab pull” caused by the lithosphere being
pulled back into the mantle, and by the convection movement of the rocks of the
asthenosphere, creating new seafloor at mid ocean ridges. The heat that creates the
movement of the plates is from both the heat of the core and heat generated from
radioactive decay of elements like uranium.
http://www.physicalgeography.net/fundamentals/10i.html
Constructive (divergent) plate margins:
Thinning of the lithosphere at constructive plate margins leads to a lowering of pressure.
This causes partial melting of the rocks of the mantle (peridodite).
Partial melting splits the mantle rock into two fractions each with a different composition
from the parent rock. The molten fraction rises and enters the magma chamber. The
minerals with the highest melting point crystallise first and can settle out of the magma. This
changes the composition of the magma leading to the formation of gabbro and basalt on
cooling, creating new seafloor and a mid ocean ridge.
Subduction zones: the formation of andesites and granites
Subduction is when one plate moves underneath another. At subduction zones the ocean
floor and its sediments partially melts due to
 Increased friction as it moves down into the mantle

presence of water which lowers the melting point of the rocks.
This leads to the formation of intermediate and acid magma which rises and cools to form
continental rocks such as andesite and granite.
Perth College UHI
10
TYPE REF HERE
Collision of two oceanic plates.
One plate starts to move down into the mantle forming an ocean trench and starts to melt
The magma starts to rise and forms intrusive rocks or is erupted from volcanoes as lava.
Eventually the rocks rise above the water creating an island arc.
http://www.physicalgeography.net/fundamentals/10i.html
Collision of an oceanic plate with a continental plate.
The oceanic crust is denser than the rocks of the continent. This forces the ocean plate to
slide underneath the lighter continental plate forming a trench. The plate melts and magma
creates intrusive rocks or is erupted as lava from volcanoes forming a volcanic arc(also
referred to as a magmatic arc)
http://www.physicalgeography.net/fundamentals/10i.html
Collision of two continental plates.
This took place in Scotland during the Caledonian Orogeny. The type of plate collision
forms Fold Mountains and results in widespread regional metamorphism as rocks are
buried during the collision. Melting of the plate results in intrusive and extrusive rock
formation, further raising the height of the mountain range
http://www.physicalgeography.net/fundamentals/10i.html
TYPE REF HERE
11
Perth College UHI
http://www.mme.state.va.us/Dmr/DOCS/Geol/Images/cambrian.gif
Diagrams illustrating the closure of the Iapetus ocean and the start of the Caledonian
Orogeny. Notice that Atlantic Ocean does not exist!
A summary of the process of plate tectonics can be found at:
http://www.open.edu/openlearn/science-maths-technology/science/geology/the-mechanism-behind-platetectonics#main_header
Plate tectonics and Metallic Mineral Resources
Our modern lifestyle requires a huge range of metals for making things like machines,
bridges and everyday items such as mobile phones. Metals are scattered unevenly
throughout the earth crust in amounts that are often too low to be economically mined. In
order to form an ore deposit the metal must be concentrated above its average crustal
concentration
Plate tectonic is largely responsible for the formation of our major metallic reserves.
Hydrothermal deposits can create ore deposit, such as copper and gold. Igneous
intrusions from a subducting plate like the granite batholthis (shown in the diagram below),
are a source of heat, water and metals. The sequence of formation of a hydrothermal vein
is:
1. Outer part of intrusion crystallises first. Metals and water collect at the top
2. The metals in the magma are now concentrated in the hydrothermal fluid at the end
of crystallisation
3. As the intrusion cools, cracks form and the hydrothermal solution moves into the
surrounding rocks. Groundwater may also be drawn into the intrusion and a
hydrothermal circulation system set up
4. As the hydrothermal fluid moves away from the intrusion it cools and solidifies in
cracks creating ore deposits
What is the difference between an “ore mineral” and an “ore?”
An ore is a mixture of ore minerals and waste materials (called gangue)
An ore mineral is a mineral from which metal may be economically extracted
Perth College UHI
12
TYPE REF HERE
Research Activity:
1. Create a case study of copper ore formation and extraction in South America and
consider some of the environmental impact surrounding this
1.
2. the relationship between plate tectonics and the global distribution of copper
Barytes: formation, discovery, extraction, processing and uses
Most baryte is mined from layers of sedimentary rock which formed when baryte
precipitated onto the bottom of the ocean floor. It can also form in veins from hydrothermal
fluids. Baryte is mineral composed of barium sulphate (BaSO4). Its main properties are its
high specific gravity (4.5), very low solubility; it is non-toxic, and also chemically and
physically unreactive. It is extracted by both surface and underground mining, followed by
simple physical processing methods to produce correctly sized product and to remove
extraneous materials. Some 80% worldwide is used as a drilling fluid in oil and gas
exploration. It is also used for barium meals at it can shield body parts from x rays
TYPE REF HERE
13
Perth College UHI
Shale oil and gas: formation, discovery, extraction, processing and uses
Research
Oil and gas reserves are also related to plate tectonic activities. Read the article (ignore the
adverts!) on plate tectonics and the distribution of oil reserves
http://www.scientificamerican.com/article/why-is-oil-usually-found/
A detailed description of crude oil formation and sedimentary basin can be found at:
http://energy.usgs.gov/GeochemistryGeophysics/GeochemistryResearch/OrganicOriginsof
Petroleum.aspx
Important terms:
Shale Oil is oil extracted and refined from oils shales
Shale oil forms from marine micro-organisms (mostly plankton) that have been deposited
on the ocean floor then buried in condition without oxygen that prevents them from
decomposing. As more sediment is deposited, burial creates heat and pressure that
changes the organic remains into kerogen
Oil shale is a general term for any fine grained sedimentary rock containing significant
amounts of kerogen (that did not undergo enough maturation to produce petroleum)
Maturation process is where plankton is converted first into kerogen, then into petroleum
by the effects of temperature and pressure during burial
A source rock is an organic rich mudstone or shale containing abundant plankton that
formed in a low energy, anoxic (lacking oxygen) marine conditions
Porosity and Permeability
Porosity is a measure of the space in a rock and is a dependant on the number and size of
the pores. Permeability is a measure of how easily fluids can move through a rock. It is
dependent on the size of the pores and. how well the pores are connected. These
properties are very important in deciding how a rock would perform as a building material,
aquifer and in the creation of an oil and gas reserve
http://petroleum101.com/what-is-a-petroleum-reservoir/
Text below on shale gas is taken from
http://www.bgs.ac.uk/shalegas/
Perth College UHI
14
TYPE REF HERE
Conventional gas comes from a ‘source’ rock that was buried and heated at considerable
depth (up to thousands of metres below the surface). Temperature increases with depth,
and hydrocarbons, such as oil and gas, are released from the source rocks at different
rates depending on how fast the rocks are heated. Due to the pressure underground, these
hydrocarbons migrate upwards and may find their way into a porous ‘reservoir’ rock. If this
is overlain by an impermeable ‘cap’ (or ‘seal’) rock the hydrocarbons become trapped. The
hydrocarbons are extracted by drilling through the cap rock into the reservoir. These
hydrocarbons, which can be relatively easily recovered, are known as conventional
hydrocarbons and have been exploited for more than 100 years. North Sea gas is a
conventional hydrocarbon.
Shale Gas
With ‘unconventional’ hydrocarbons, and shale gas in particular, the rock which contains
the hydrocarbons is virtually impermeable and so acts as hydrocarbon source rock,
reservoir and seal. The gas is both produced and trapped within the shale. It is only when
the shale is drilled and artificially fractured that the gas is released from the rock and can be
extracted. The process of artificially fracturing the rock is called ‘fracking’.
Sources http://www.bbc.co.uk/news/uk-14432401
http://www.bgs.ac.uk/research/energy/shaleGas/basics.html
Read the article and watch the video clip then answer the following questions
1.
2.
3.
4.
5.
6.
7.
What is fracking?
Why is it called fracking?
Briefly describe the processes
What is shale and shale gas?
Describe how shale gas was formed
Give one advantage of fracking
Describe potential / actual environmental problems associated with fracking
http://thebreakthrough.org/blog/Where_the_Shale_Gas_Revolution_Came_From.pdf
More background reading from USA
TYPE REF HERE
15
Perth College UHI
http://www.cfr.org/energy-and-environment/hydraulic-fracturing-fracking/p31559
Aluminium formation, discovery, extraction, processing and uses
Almost all aluminium every produced has come from bauxite. Bauxite is a rock formed from
the weathering of laterite soil that has been severely weathered in a wet tropical or
subtropical climate. It is the primary ore of aluminium. It consists mostly of the minerals
gibbsite Al(OH)3,
Visit the site below and make summary notes on extraction processing and use:
http://www.hydro.com/en/About-aluminium/How-its-made/
General background infomation on minerals can be found at
http://www.bgs.ac.uk/mineralsuk/mineralsyou/wheredo.html
Clay: formation discovery, extraction and uses
The term "clay" is applied both to materials having a particle size of less than 0.002 mm
and to a group of minerals that have similar chemical compositions and a layered crystal
structural.
Activity
Find an electron microscope image of a clay minerals that illustrates the layered crystal
structure
Clay has been used for 1000`s of years for making bricks, pots and ceramics.Clay has also
many other uses including firebricks, bricks, tunnel and ditch support, , fuller’s earth, cat
litter, fining beer
Physical properties
Clay minerals all have a great affinity for water. Some swell easily and may double in
thickness when wet. Most have the ability to soak up ions (electrically charged atoms and
molecules) from a solution and release the ions later when conditions change.
Environmental industries use clay to produce liners for containment of waste. The
absorptive properties of bentonites and fuller's earth make them ideal for such diverse uses
as drilling mud and absorbing animal wastes
Weathering
Weathering of rocks and soil is the primary way and clay minerals form. .For example
bentonite clays usually form from altered volcanic ash The example below illustrates how
clay minerals can form from granite, a very hard igneous rock
Examine a specimen of granite. If you look closely you will see it contain three minerals
What are the colours of the 3 minerals, can you identify them?
You should have been able to see
Perth College UHI
16
TYPE REF HERE



Quartz, which is glassy
Mica, which is black and “shinny”
Feldspar, which is white coloured mineral
Physical weathering breaks the rocks down to smaller and smaller particles. Physical
weathering of the quartz forms sand and silt
Chemical weathering alters the mineral feldspar to the clay mineral kaolinite, which has a
layered structure
This process is called hydrolysis.
Feldspar + Water  Kaolinite (Clay)
Mica can weather to clay minerals in a similar way to feldspar
The aims of geodiversity conservation

Recognizing

Protecting

Managing sites
Nationally important geological sites are protected as Sites of Special Scientific Interest
(SSSIs). SSSI sites were selected through the Geological Conservation Review (GCR).
Criteria:
1. Sites of importance to the international community of Earth scientists
2. Sites which are scientifically important because they contain exceptional features
3. Sites which are nationally important because they are representative of an Earth
science feature, event or process which is fundamental to Britain’s Earth history
e.g. Kinnoul Hill and Ryhnie Chert
http://aberdeen.ac.uk/rhynie/
RIGS( Regionally Important Geological and Geomorphological Sites) are non-statutory
designation for local sites out with the SSSI protected sites. RIGS can be listed on local
authorities' development plans.
World Heritage Sites
Selected by UNESCO as places of ‘outstanding universal value' can be cultural or natural
features
e.g. Jurassic Coast
Geopark are areas with an outstanding geological heritage. To be selected as a Geopark the
area should be managed in a way that:

conserves geological heritage
TYPE REF HERE
17
Perth College UHI


promotes the enjoyment and understanding of geology, and
supports sustainable development.
Geoparks have a management plan based on sustainable “geotourism”
Unesco Geoparks
http://www.europeangeoparks.org/isite/home/1%2C1%2C0.asp
Northwest Highlands
http://www.northwest-highlands-geopark.org.uk/
Knock and Lochan
http://www.knockan-crag.co.uk/Geopark.asp
English Riveria
http://www.englishrivierageopark.org.uk/
Fossil Code
The fossil code aims is to encourage sustainable fossil collecting., provides advice on best
practice in the collection, identification, conservation and storage of fossil specimens found
in Scotland. The Code also aims to enhance public interest in the fossil heritage of Scotland
and promote this resource for scientific, educational and recreational purposes.
http://www.snh.org.uk/pdfs/fossil_code/fossilcode_08.pdf
The Geological Carbon Cycle
1. Describe how limestone acts as a carbon store in the carbon cycle.
2. Describe how volcanoes can release C02 into the atmosphere.
3. Does the combustion of fossil fuels have an effect on the carbon cycle? Give a
reason for your answers.
Perth College UHI
18
TYPE REF HERE
Revision exercise: Create a summary table
Mineral
Formation
Extraction
Uses
Bauxite
Baryte
Clay
Sale oil
Shale gas
Copper
ore
TYPE REF HERE
19
Perth College UHI