Geology and Past Processes (Edexcel GCSE Geography: B (1GB0))

• 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

Map of upland and lowland UK showing glacial limit and major rivers

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

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

Rock Type	Hardness	Resistance to Erosion and Weathering	Permeability	Found Mainly	Landscape Feature
Igneous	Hard	Resistant	Impermeable	Upland	Granite landscapes are usually boggy and badly drained
Metamorphic	Very hard	Very resistant	Impermeable	Upland	Badly drained and boggy
Sedimentary	Hard to very soft	Less resistant	Permeable Clay is impermeable	Lowland	Limestone features are caves and karst Chalk landscapes tend to be dry valleys and gentle hills inland and steep cliffs at the coast Clay collapses easily when wet (slumping) and form gentle, wide landscapes, which are frequently waterlogged