Date post: | 27-Dec-2015 |
Category: |
Documents |
Upload: | claud-hodge |
View: | 218 times |
Download: | 0 times |
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 RocksThese 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 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.
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 SceneryMalham 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 RocksThese 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 WeatheringFreeze 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 SketchWeathering Sketch