Geology & Past Processes (Edexcel GCSE Geography B)

UK's Physical Landscape

• A landscape is defined as:

The character of an area, resulting from the action and interaction of natural and human elements

• A landscape's character will depend on its initial geology, which gives a landscape its relief, which in turn attracts human action/interaction, for example:

  • Slate, (a type of resistant rock) found in the mountains of North Wales, attracted people to quarry for roofing material and generated over four-fifths of all British slate during the Industrial Revolution

Past tectonic activity

• Plate movement has moved the UK from the tropics

  • It was partially submerged in warm shallow water which formed the limestones of the Peak District, parts of south Wales and south-west England

• The chalks and clays of England are the youngest rocks in the UK

  • These formed in the swamps and shallow seas before the tectonic plates moved the UK to its present position

• When the plates collided, it forced the rocks to fold and uplift creating the mountain ranges of the uplands:

  • Scottish Highlands, Snowdonia, and the Lake district etc. 

• The pressure and heat created the slate, shale and schist of the uplands

• The UK used to be much closer to a plate boundary than it is now, and volcanic activity formed the granite (igneous rock) of the upper landscape:

  • The Giant's Causeway in Northern Ireland is made of huge hexagonal columns of basalt

Glaciation

• During the last Ice Age, both upland and lowland UK landscapes were affected

• The Tees-Exe line roughly marks the southern limit of the UK's glaciation

• Ice sheets covered the upland UK with glaciers forming distinctive places such as Snowdonia and the Lake District

• Lowland UK was affected through a glacial wash of clay and debris

Characteristics & Distribution of UK's Main Rock Types

Rock groups

• There are three types of rock, and each depends on how its formation: 

  • Igneous rock

    • Form when magma from the mantle cools down and hardens

    • As it cools, crystals form in the rock

    • Igneous rocks are hard and more resistant to erosion e.g. granite and basalt

    • Mostly found in the northern upland areas of the UK

• Sedimentary rock

  • Layers of sediment are compacted together until they become solid rock

  • There are two main types in the UK:

    • Limestone and chalk come from the tiny shells and skeletons of dead sea creatures

    • Limestone is harder than chalk, but both are less resistant to erosion (softer compared to granite)

    • Limestone and chalk are relatively strong and permeable

    • Clays and shales are made from mud and clay minerals, are softer than limestone and chalk and impermeable 

    • Found mostly in the UK's lowland areas of the south, southeast and central UK

    • Clay landscapes are typically wide, flat plains

• Metamorphic rock

  • When rock (igneous, sedimentary or older metamorphic rock) is put under pressure and heat (but not melted), the original rock becomes a new type of rock

  • This new rock becomes harder and more compact e.g. shale becomes slate and with more pressure and heat, slate becomes schist

  • Found within the upland areas of the UK

  • Very strong and resistant to erosion or weathering

Geology = landscape

• Stronger, more resistant rocks tend to produce highland areas

• Weaker rocks tend to form lowlands

• Permeability is whether a rock allows water to pass through it

  • Water will pass through permeable rocks

  • But impermeable rocks won't let water through

• The permeability of rocks determines how wet or dry the surface of a landscape is

  • Limestone is a permeable rock that tends to form dry uplands areas with few streams and thin soils

  • Clay is impermeable which produces wet lowland areas

  • Granite landscapes are usually boggy and badly drained as granite is impermeable