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Changing landscapes of the UK (Types of rock (Sedimentary - rocks formed…
Changing landscapes of the UK
Types of rock
Sedimentary - rocks formed from sediment that have settled at the bottom of a body or water, and have been compressed over millions of year - usually have layers, often contain fossils, different colours eg. chalk, sandstone
Igneous intrusive rock - igneous rock that cools slowly deep underground in a warm place to form large crystals
Extrusive igneous rock - igneous rock that cools quickly above the ground where it is cool, forming small crystals
Igneous rocks are formed when magma from the mantle cools - they are resistant, don't contain fossils eg. granite or basalt
Metamorphic rock - These have been treated to tremendous heat and/or pressure, causing them to change into a hard rock. Usually resistant to weathering and erosion - eg. marble and slate
Contact metamorphism - where rock minerals and textures are changed mainly by heat due to contact with magma
Regional metamorphism - where rock minerals and textures are changed by pressure due to plate boundaries
Igneous rock formations
Batholith - large area of igneous intrusive rock that forms from cooled magma in the earths crust. Exposed through erosion
Dyke - vertical intrusions with horizontal cracks. They cut across bedding planes of the rocks into which they have been intruded
Sill - horizontal intrusion with vertical cooling cracks
Glacial formations
Hanging valleys - when a U-shaped valley meets the sea, but the U shaped valley is higher then the sea-level at the coast, so ends with a waterfall
As the main glacier erodes, the original tributary is left higher up the stepper sides of the glacier as its glacier has less erosional power
U-shaped valleys - formed by the glacier eroding the walls of the valley until it has gone from a V shape to a U shape
Rock steps - formed when a glacier erodes the softer rock further down than the harder rock, so the harder rock remaining up the valley are rock steps
Erratics - large rocks that were picked up the glacier and transported down the valley for some time until they were deposited
Scree - loose stones which are formed from freeze-thaw weathering
