Landscapes of the UK Flashcards
What make up the earth’s crust?
The 3 main rock types
Metamorphic
Igneous
Sedimentary
What are the main rock types characterised by?
The different processes that formed them
Formation of sedimentary rocks
Formed of small particles that have been eroded, transported and deposited in layers (such as sandstone) or from the remains of plants and animals (such as limestone and chalk)
Sedimentary rocks characteristics
Less resistant Softer rocks Permeable More easily eroded that metamorphic or igneous Therefore work down more rapidly forming lowland landscapes No crystals Contain fossils Form in layers
Formation of igneous rocks
Created by volcanic activity when magma or lava cools forming rocks made of crystals that are usually hard
Eg granite and basalt
Igneous rocks characteristic
More resistant
Harder
Impermeable
Contain crystals
Formation of metamorphic rocks
Layers of sedimentary rocks are so deep in the earths crust that they become exposed to huge heat and pressure which transforms them into metamorphic rocks
Eg shale compressed into slate or limestone transformed into marble
Characteristic of metamorphic rocks
Form in layers
Crystals
More resistant
What helped shape the geology and landscapes of today?
Millions of years ago Britain was close to plate boundaries
There were many active volcanoes and plate movements which caters massive folds and faults in the rocks and mountains
Example of a diverging plate boundary
50-60 million years ago, diverging plate boundaries caused Atlantic Ocean to open
Rising lava created Giant’s Causeway
Where are UK upland areas?
North Western areas- Northern Scotland (Cairngorms)
Lake District
North Wales (Snowdon)
Dartmoor in Devon
What are UK upland areas formed of?
Harder resistant rock which have eroded at a much slower rate
What created UK upland areas?
300 years ago tectonic processed caused molten magma under intense pressure to rise through Earth’s crust
Some magma reached surface as lava
Some cooled and solidified underground creating mounds of resistant rock
Less resistant rock surrounding mounds eroded leaving areas of high relief
How did lowland areas of the UK form?
250-350 million years ago when sediment fell to the sea floor creating sedimentary rocks
Where are lowland areas of the UK made from sedimentary rocks?
North and South Downs in south east England
What are the North and South Downs formed of?
Hills formed of chalk with even softer clay in the valleys between them
Area of the UK with metamorphic rocks
North West Scotland
An example of harder sedimentary rocks
Carboniferous limestone
How did Carboniferous limestone form?
250-350 million years ago when Britain was surrounded by warm tropical seas rich in plant and animal life
When the plants and creatures died, the calcium in their shells and skeletons built on layers on the seabed
Formed limestone made of calcium carbonate
When did Dartmoor form?
290 million years ago when a massive dome of magma developed underground
How did Dartmoor’s famous tors form?
As the magma dome cooled and contracted it formed granite
Cracks known as joints developed
Weaker joints made the rock vulnerable to freeze thaw weathering which caused fragments of rock to become detached
Over time, as the granite become exposed on the surface, erosion and mass movement processes like slumping removed the broken up granite
Blocks of rock with fewer joints are left behind and the largest blocks are left standing
Example of Dartmoor’s famous tors
Bowerman’s Nose
What are the tors surrounded by?
Clitter slopes covered in smaller rocks
Why do the tors continue to change?
The influence of freeze thaw and chemical weathering