Topic 4 - The UK's Evolving Physical Landscape Flashcards
Three types of rocks are…
- Igneous
- Sedimentary
- Metamorphic
How are igneous rocks formed?
Igneous rocks are formed when molten rock (magma) from the mantle cools down and hardens. The rock forms crystals as it cools.
Examples of igneous rocks…
Granite and Basalt
How are sedimentary rocks formed?
Sedimentary rocks are formed when layers of sediment are compacted together until they become solid rock. They can also be formed from sediments eroding and being deposited by rivers.
The two types of Sedimentary rocks are?
- Carboniferous limestone and chalk: They are formed from tiny shells and skeletons of dead sea creatures. Limestone is quite hard, but chalk is a much softer rock.
- Clays and shales: They are made from mud and clay minerals. They are very soft.
How are metamorphic rocks formed?
Metamorphic rocks are sedimentary rocks that are heated and compressed during igneous activity. Heating and compression harden them and make them resistant.
Examples of metamorphic rocks are…
Slate and marble
What is mechanical weathering?
Mechanical weathering is the breakdown of rock without changing its chemical composition.
What happens during salt weathering?
1) the seawater gets into cracks
2) when the water evaporates, salt crystals form. As the salt crystals form they expand, which puts pressure on the rock
3) repeated evaporation of saltwater and the forming of salt crystals widens the cracks and causes the rock to break up
What is chemical weathering?
Chemical weathering is the breakdown of rock by changing its chemical composition.
What happens during chemical weathering?
1) seawater and rainwater have carbon dioxide dissolved in them, which makes them weak carbonic acids.
2) carbonic acid reacts with rock that contains calcium carbonate, e.e. Carboniferous limestone, so the rocks are dissolved by the rainwater
What is biological weathering?
Biological weathering is the breakdown of rock by living things e.g. plant roots break down rocks by growing into cracks on their surface and pushing them apart
What is mass movement?
Mass movement is when material falls down a slope
What are the three types of mass movement?
Slides
Slumps
Rockfalls
What is hydraulic action?
Hydraulic action is when the force of the water breaks particles away from the river channel
What is solution?
Solution is when river water dissolves some types of rocks e.g. chalk and limestone
What is abrasion?
Abrasion is when eroded rocks are picked up by the river and then scrape and rub against the channel, wearing it away. Most erosion happens by abrasion
What is attrition?
Attrition is when eroded rocks are picked up by the river, smashed into each-other and break into smaller fragments. Their edges are also rounded off as they rub together. The further material travels, the more eroded it gets - attrition causes particle size to decrease between a rivers source and its mouth.
Where do headlands and bays form?
Along discordant coastlines
What can headlands be eroded to form?
Caves, arches and stacks
What is transportation?
The movement of material
