Geology
The study of rocks
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.
How rocks are formed
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
Igneous Landscapes
Dartmoor
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.
Sedimentary Rocks
Sedimentary Rocks
These rocks are formed
under water in rivers
lakes and oceans.
They build up in layers.
Examples include:
Sandstone, Limestone
and Chalk.
Limestone Scenery
Malham in Derbyshire
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.
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.
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.
Erosion by water
Erosion by Wind
Erosion by Ice
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.
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.
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.
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.
Rock weathering in Australia
Weathering Sketch
Weathering Sketch