changing landscapes/coasts Flashcards
how is igneous rock formed and what are the characteristics
when molten rock (magma) from the mantle cools down and hardens, rock forms crystals as it cools
- usually hard e.g granite and basalt
how is sedimentary rock formed and what are the characteristics
layers of sediment are compacted together until they become solid rock
- usually softer and easily eroded but some are relatively hard
- e.g sandstone, chalk
how is metamorphic rock formed and what are the characteristics
when other rocks are changed by heat and pressure and the new rocks broken harder and more compact
e.g clay -> slate + more pressure n heat -> schist
how have active volcanoes shaped the landscape of the uk?
volcanic eruptions formed through earth’s crust which cooled to form igneous rocks e.g granite and basalt
how have plate collisions volcanoes shaped the landscape of the uk?
- collisions between tectonic played caused the rocks to be folded and uplifted forming mountain ranges with some areas remaining as uplands (scottish highlands e.g)
- intense heat n pressure caused by pc formed hard metamorphic rocks in N scotland
how have active plate movemos shaped the landscape of the uk?
- carboniferous limestone formed in warm shallow seas (seen in uplands of peak district in N england + S wales
- chalks n clays formed in shallow seas and swaps and form lowland landscapes
what are the characteristics of granite
- igneous + forms upland landscapes
- lots of joints (not evenly spread) (areas w more joints wear down faster, areas w less = weathered slowly)
- impermeable - doesn’t let water through, creating moorlands, w low growing vegetation
what are the characteristics of basalt?
- igneous + made of volcanic lava
- v hard + impermeable, forms escapements in uplands n cliffs at coasts
- as lava cools it forms columns
what are the characteristics of chalk?
- sedimentary, forms hills in lowlands + cliffs at coast
- chalk is permeable, water flows through it n emerges as a spring where it meets impermeable rock
what are the characteristics of sandstone?
- sedimentary, made from sand
- softer stand stones form lowland landscapes
- harder sandstones form upland landscapes
- porous, has small gaps so it can store water in underground aquifers
what are the characteristics of late and schist?
- metamorphic rocks
- slate: forms in layers creating weak planes in rock, hard + resistant to weathering but easily split into thin slabs
- schist has bigger crystals and splits easily into small flakes
- both form rugged upland landscapes, impermeable which lead to waterlogged and acidic soils
how was the landscape also shaped by ice?
- during last glacial period ice covered uk, able to erode landscape + carved out u-shaped valleys in upland areas (e.g lake district)
- glaciation affected lowland areas, it deposited material as it melted
what physical processes alter the landscape?
- weathering
- erosion
- post-glacial river processes
- slope processes
how have physical processes interacted to create upland areas (snowdonia) ?
- freeze-thaw w occurs on back wall of corrie n as rocks are broken up, there are rock falls, forming scree slopes
- lots of rain + impermeable rocks + lots of strreams eroding sides of corrie and forming gullies
- llyn idwal sits in a corrie that was hollowed out in glacial times
how have physical processes interacted to create lowland areas (the downs and the weald)
large rivers meander on impermeable clay, widening valley floor
- uk + wet climate, leads to flooding, n overflowing river deposits silt onto valley floor forming a flood plain
how have humans changed the landscape through agriculture?
- cleared forest to make space for farming, hedgerows and walls built to mark out fields
- landscapes adapted for different types of farming
-> arable (growing crops, flat land good soil)
-> dairy (warm wet areas, grassy fields)
-> sheep (led to lack of trees as they vare eaten or trampled on before maturing)
how have humans changed the landscapes through forestry?
forestry = management of areas of woodlands, used for timber recreation or conservation
little deciduous woodland left, coniferous forests planted for timber
- c trees planted in straight lines, when area is felled, landscape left bare affecting drainage and lead to increased erosion
how have humans changed the landscapes through settlement?
- land concreted over for roads and buildings, affecting drainage patterns
- rivers diverted through underground channels
- river channels straightened or embankments built to prevent flooding
how is rock broken down by mechanical weathering?
mechanical w - breakdown of rock w/o changing comp comp
- salt weathering: 1. seawater gets into cracks into rock
2. water evaporates, salt crystals form, expands and puts pressure on the rock
3. repeated evaporation and forming of salt crystals widens crack and causes the rock to break up
how is rock broken up by chemical weathering?
cw - breakdown of rock by changing its comp.
- 1. rainwater has CO2 dissolved in it + weak carbonic acid
2. carbonic acid reacts w rock that contains calcium carbonate e.g chalk, so rock dissolves
how is rock broken up by biological weathering?
bio w - breakdown of rock by living things
- animals e.g rabbits burrow into soil on cliff tops
- plant roots breakdown rocks by growing into cracks on their surfaces and pushing them apart
what is mass movement?
the shifting of rocks and loose material down a slope and happens when the force of gravoty acting on a slope is greater than the force supporting it
- cause coasts to retreat rapidly
what are the 4 processes of erosion?
hydraulic action - (waves crash against rock + compress air in cracks, putting pressure on rock, repeated compression widens crack making bits of rocks break off)
abrasion - (eroded particles in water scrape n rub against rock removing small pieces)
- attrition (eroded particles smash into each other, rounding the edges and breaking into smaller fragments)
- solution (dissolves CO2 makes water slightly acidic, acid reacts w rocks n dissolved them)
what are the characteristics of destructive waves?
high frequency (10-14 wpm)
high + steep
backwash (movement down beach) is more powerful than swash (movement up beach) -> material is removed from coast