4a - uk physical Flashcards
(21 cards)
how is the uk geologically split?
- the top half above the T-E line is mainly igneous and metamorphic rocks, forming UPLAND landscapes
- the bottom half is mainly sedimentary rocks, forming LOWLAND landscapes
how is igneous rock formed?
volcanic magma cooling (e.g granite)
how is metamorphic rock formed?
other rock types being changed by heat or pressure (e.g schist/slate)
how is sedimentary rock formed?
compression of deposited sediment (e.g clay/chalk)
how has glaciation affected the UK in the past?
the top half of the UK used to be glaciated in the last Ice Age - it used to press down on landscapes, eroding it. though the bottom half wasn’t covered in ice sheets, sediment eroded by the northern areas were dumped and washed over southern areas, freezing the south.
what landscapes does chalk typically form and why?
chalk is strong and permeable, so forms cliffs when it occurs at coastlines (only found in lowland britain)
what landscapes does clay typically form and why?
clay is weak and impermeable, so its landscapes are typically wide and flat plains with lots of lakes, streams and rivers (found all over britain)
what landscape could granite form and why?
granite is resistant to erosion, but susceptible to chemical weathering. it is also impermeable and badly drained, so TORS are features of some granite landscapes - towers of granite chemically weathered into blocks
how do metamorphic rocks change?
- clay forms slate
- shale forms schists
(metamorphic rocks are very strong and very resistant to erosion and weathering)
what are some glacial processes?
- freeze thaw : water in cracks thawing and expanding, eventually breaking the rock apart
- plucking : as a glacier moves, rock stuck to it moves downhill
- abrasion : plucked rocks rub against surrounding rock as glacier moves
describe what isostatic changes are?
- since the north was glaciated, it has since been rising when the glaciers sink, and the south is beginning to sink - FLOOD
what role has extrusion had on the UK’s physical landscape?
- EXTRUSION : magma being ejected and cooling to produce layers of igneous rock - that is how the Scottish highlands were created
what is continental drift?
the spreading of the countries - the scottish highlands that used to be on active plate boundaries ( causing the extrusion ), no longer is
what is intrusion?
- INTRUSION : the formation of igneous rock under the surface of existing rock - a large intrusion is called a BATHOLITH
how and where do clitter slopes form? - UPLAND LANDSCAPE
clitter slopes form when solifluction ( the very slow downslope movement of saturated soil ) transports large boulders down a slope
sub-aerial weathering processes?
- mechanical weathering : most common in cold climates when frozen water in freeze-thaw, the crack expands and pieces of rock fall off
- chemical weathering : e.g granite converting to soft clay after reaction with water / limestone dissolved by carbonation from co2 and rainwater
- biological weathering : plant/animal action - e.g tree roots widen gaps in rocks, or micro-organisms eating away at rock
- mass movement : downhill movement of material under the influence of gravity - e.g slumps of loose, wet rock sliding down a curved slip plane (STRESS>STRENGTH FOR COASTS)
how does a spring line settlement form? - LOWLAND LANDSCAPE
when precipitation falls on permeable chalk, water infiltrates, flowing downhill until it reaches the impermeable clay. this is where it springs out, and spring line settlements develop at the bottom of the scarp
what are orogenies?
when tectonic plates fold over one another, mountains are formed
how has agriculture changed the landscape of the new forest?
- trees have been cleared in areas of well-drained soils for agriculture and growing crops
- livestock roam and graze, preventing more tree growth
- HOWEVER only 5% of the population is employed by agriculture
how has forestry changed the landscape of the new forest?
- growth is encouraged, but a lot of trees are planted
- an area of outstanding national beauty, so partially is preserved
- significant commercial forestry (e.g timber production), in enclosed areas has decreased the forestry
how has settlement changed the landscape of the new forest?
- there are huge inequalities : well-paid committees and second homes vs poorer paid agricultural workers
- more than 34000 people live in the NF, but only 3 settlements have more than 3000 people
- the NFNPA restricts building to protect the atmosphere
