- igneous, intrusive.
- vertical joints from where granite cooled and contracted (vertical) and pressure from overlying rocks (horizontal)
FORMATION OF A GRANITE TOR
- sediment builds on top of granite but is eroded.
- closely spaced joints weathers more quickly than widely splaced.
- tor is left
- mass movement moves weathered rock onto ground called scree.
- continuous process
- sheep farming
- army training
also for paint, china, medicine, beauty products, roads, gravestones, work tops, fireplaces
chalk and clay
sedimentary, exposed at slight angle because rocks folded during teconic activity.
ESCARPMENTS AND VALES
- horizontal layers are tilted diagonally by tectonic movements
- chalk = resistant
- clay = soft
- clay eroded more quickly leaving chalk escarpments (hills) - dip slope, scarp slope, vale
- water flows through chalk and emerges where permeable chalk meets impermeable clay. - spring line.
- linear settlements used to occur near the spring line
- dry valley formed - dont have a river flowing through because the water is underground
USES of CHALK
- farming - sheep on scarp, crops on dip
as well as cement and flint for building
USES of CLAY
- dairy farming
- cement works
as well as pottery, bricks and roof tiles
LIMESTONE PAVEMENTweathering enlarges joints to form deep narrow grooves called GRYKES. Blocks between are called CLINTS.
when river reaches limestone it starts to disappear down a swallow hole/sink
water flowing below ground dissolves limestone forming underground caves/caverns. Caves enlarged by roof collapse.
- water seeps through limestone which contains dissolved minerals.
- when water drips into cavern the mineral solidifies and bulds up over time
- stalaCtites (ceiling)
- stalagmites (floor)
- where stalactites and stalagmites join is called a pillar
rivers pop out at the surface when limestone is on top of impermeable rock.