geography rocks
how do dry valleys form?
During the ice age, underground water remained frozen while surface water melted. This forced the flow of meltwater over the surface causing erosion of valleys, when the underground water melted, the surface water moved under ground leaving dry valleys
what is freeze thaw weathering?
When water enters the cracks of rocks and freezes, expanding its volume by 9%, when it then melts and contracts it leaves the hole bigger. repeated freezing and thawing causes the rocks to crack.
what is an aquifer?
a body of permeable rock which can contain or transmit groundwater.
define curtain
a broad deposit of calcite usually formed when water emerges along a crack in a cavern
what are the properties and characteristics of limestone?
a hard grey sedimentary rock, full of (vertical) joints and (horizontal) bedding planes, in a blocky formation, can form sink holes and caves
define cavern
a large underground cave
define resurgence
a stream that emerges from underground
define stalagmite
a stumpy calcite feature formed on a cavern floor
how do stalagmites form?
a weak carbonic acid dissolves the calcium carbonate in limestone, it then seeps through into the caves below and drips down on to the floor reforming into calcium bicarbonate
how do stalactites form?
a weak carbonic acid dissolves the calcium carbonate in limestone, it then seeps through into the caves below and reforms into calcium bicarbonate while hanging down from the roof forming stalactites
define swallow hole
an enlarged joint into which water falls
define stalactite
an icicle-like calcite feature hanging down from a cavern roof
how do limestone pavements form?
areas with less joints are weathered less than area with more and after long periods of time the areas of more joints area weathered away leaving just the areas without, the gaps are called grikes and the blobs left are called clints
what is carbonation?
carbon dioxide and water react to form a weak carbonic acid. this reacts with the calcium carbonate in the limestone to form calcium bicarbonate. this wears away the rock.
what are the properties and characteristics of granite?
impermeable, igneous rocks that contain rock pits, dull spots or fissures
what are the uses of chalk areas?
pastoral farming - mainly sheep and race horses,settlements - spring line (where permeable rock meats impermeable a line of springs is formed), race horse training, quarrying - cement
what are the properties and characteristics of chalk?
permeable, sedimentary, where chalk meets an impermeable rock it forms a line of springs, gentle rolling hills
what are the uses of granite areas?
quarrying - building blocks, farming-sheep, mining - copper and tin, tourism and the extraction of china clay
what are the uses of limestone areas?
quarrying - cement and fertiliser, farming - mainly sheep and tourism - walking, camping, climbing, pot-holing and caving.
what is weathering?
the breakdown of rocks (in situ) into smaller fragments
define pillar
where a stalactite meets a stalagmite, a calcite feature that stretches from floor to ceiling in a cavern