UK landscapes Flashcards
What are igneous rocks?
Igneous rocks - these rocks are a result of volcanic activity in the past, when Britain was close to a plate boundary. Some of the igneous rocks are due to lava erupting at
constructive plate boundaries
. When the lava reached the surface, it cooled and solidified to form basalt rock. An example of this is the Giant’s Causeway in Northern Ireland.
Other rocks are formed by hot molten magma beneath the Earth’s surface cooling and solidifying as an intrusive rock under the ground, such as granite. This is later exposed as the rocks above are weathered and eroded at the Earth’s surface.
What are sedimentary rocks?
Sedimentary rocks – these are made up of small particles of sand and rock, which have been transported by the wind, rivers and ice and are usually deposited on lake or seabed. Over many millions of years, successive layers of sediments accumulate. These layers of sediments are compressed by the weight of the deposits above, into sedimentary rocks. These rocks form in layers, known as bedding planes.
When sand is compressed it forms sandstone. When mud is compressed it becomes clay. Limestone and chalk come from the remains of dead plant, animal and marine species and are rich in calcium carbonate and contain fossils. Many of these rocks were formed over 300 million years ago, in warm tropical seas during the
carboniferous period
. The existence of these rocks is evidence that Britain was at a different latitude compared to today. This suggests movement of continental areas of the globe, which is explained by the modern theory of plate tectonics.
What are metamorphic rocks
Metamorphic rocks - these are rocks that have been changed in shape and form by intense heat and pressure at a plate boundary or along a fault line. These rocks start as either igneous or sedimentary rocks and are crystallised under the intense heat and pressure conditions to form rocks such as slates,
schists
, and marble. These rocks are very hard in nature and are often used as roof material.
How are the rocks distributed?
Igneous rocks can be found mainly in upland areas in Scotland, in the Lake District in North West England and Snowdonia in North Wales and Northern Ireland.
Metamorphic rocks are found in Northern Ireland and Scotland.
Sedimentary rocks are widely found across lowland areas of England.
Where are the upland areas in the UK?
Upland areas are mainly found in:
Scotland - The Northwest Highlands, the Cairngorm Mountains, the Grampian Mountains and the Southern Uplands. Ben Nevis is the UK’s highest peak and is found in the Grampian Mountains.
England - The Pennines, Lake District, Dartmoor and Exmoor. Scafell Pike is the highest mountain in England and is found in the Lake District.
Wales - Snowdonia and the Brecon Beacons. Snowdon is the highest mountain in Wales and is found in Snowdonia.
Where are the lowland areas in the UK?
Lowland areas can be found in the following places:
around The Wash (East Anglia and Lincolnshire)
Lincolnshire
the Fens in East Anglia - the lowest place in the UK
the Midlands
the London Basin
the Vale of York
The way the landscape changes in height.
Relief.
An asymmetrical ridge separating areas of land at different heights.
Escarpment
A wide valley in between chalk and limestone escarpments.
Vale
How do chalk and clay affect lowland landscapes?
Chalk is resistant to weathering and erosion, it is only really affected by slow chemical weathering, when rainwater dissolves the calcium carbonate. The chalk forms steep escarpments, seen on the left of the image above. Softer, highly erodible clays lay below the chalk, forming low, flat vales.
How limestone pavements are made?
a limestone pavement which is formed when the joints in the limestone are dissolved away by the rainwater. Limestone is dissolved because rainwater is a weak carbonic acid. The joints which are widened and deepened by this chemical weathering are called grikes. The blocks which stick up are called clints. Plants growing in the sheltered grikes can give off acid and this will deepen the joints even more.
What are the different types of mass movement?
Rockfall
Rocks fall off the cliff face forming scree at the bottom.
Bits of rock fall off the cliff face, usually due to freeze-thaw weathering.
Mudflow
Saturated soil slides down the bedrock forming a lobe at the bottom with a stream running through.
Saturated soil (soil filled with water) flows down a slope.
Landslide
Rocks detach off the slide plane and slide down to the bottom.
Large blocks of rock slide downhill.
Rotational slip
Soil slides down a curved slip plane. The top is called the head, the bottom the foot. The soil collects at the toe. The wall of the curved slip plane is the scarp.
Saturated soil slump down a curved surface.
