Geology The study of rocks

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Geology The study of rocks
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Geology of the British Isles
The British Isles is made up of many different
types of rock. These different rock types give us
the wonderful range of scenery we enjoy.
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How rocks are formed
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Igneous Rocks
These rocks are formed when magma / lava cools
and hardens on the surface and in the
crust. Igneous rocks are very hard /
resistant. Granite is a good example. Granite is
used for buildings, roads, etc.
Intrusive feature / batholith
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Igneous LandscapesDartmoor
Dartmoor in S.W. England is an upland area over
800m high. It can be wet windy and misty but also
stunningly beautiful on clear days. It is a
National Park.
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Sedimentary Rocks
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Sedimentary Rocks
These rocks are formed under water in rivers
lakes and oceans. They build up in layers.
Examples include Sandstone, Limestone and Chalk.
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Limestone SceneryMalham in Derbyshire
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Limestone Caves
Limestone is alkaline and has a chemical reaction
with rainwater which is slightly acid. The rock
dissolves and forms amazing features like
underground caves. Stalactites and stalagmites
are special underground features.
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Metamorphic Rocks
These rocks are formed by changes in heat and
pressure. Clay can be changed into slate when
superheated. These rocks are very
resistant. Slate is a good example. It is used
for roofing.
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Weathering and Erosion
All rocks are eventually broken down even the
hardest like granite. Rocks can be broken down
by Weathering, Erosion or a combination of both.
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Erosion by water
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Erosion by Wind
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Erosion by Ice
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Biological Weathering
The roots systems of this tree are working their
way into the cracks of the rocks. They break open
the cracks and weaken the rock.
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Chemical Weathering
Pollution in the atmosphere from factories
makes all rainwater slightly acidic. CO2
SO2 When this rain falls onto limestone it
chemically dissolves it creating spectacular
underground scenery.
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Physical Weathering
Freeze Thaw Process All rocks have small cracks
in them called fissures. Water collects in the
cracks and when it is cold enough freezes. The
ice expands opening up the crack. More water
fills the crack. Ice forms and expands opening
the crack further. The process is repeated until
the rock breaks down. This process happens in
mountain regions where temperatures are low.
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Mechanical Weathering
Temperature changes can cause the rock to expand
/ contract. The layers can break away and the
rock breaks down. This can happen in desert
environments.
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Rock weathering in Australia
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Weathering Sketch
Weathering Sketch
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