3.2 Weathering and rocks Flashcards
Biological weathering
Form of weathering caused by activities of living organisms. (Chemical and physical)
Carboniferous limestone (karst)
Formed of remains of organic matter, mostly plants and shells.
Why is limestone scenery unique?
It is hard but permeable.
It dissolves very slowly in acid water.
Freeze-thaw
Form of physical weathering, common in mountains and glacial environments.
Granite
Coarse-grained, intrusive, igneous rock, typically consisting of the mineral quartz, feldspar and mica.
Joint
Vertical crack in a rock formed by compression. Weathering of joints in granite and limestone is responsible for the formation of swallow holes.
Karst
Characteristic scenery of a carboniferous limestone region with underground streams.
Mechanical (physical weathering)
Includes process like freeze-thaw and exfoliation or onion-skin.
Scree
Angular sediment that collects at the foot of a mountain range or a cliff.
Solution
Occurs on rocks like chalk and limestone that contain calcium carbonate. When dissolved in rain CO2 forms weak carbonic acid.
Tor
Isolated mass of rock, often granite, left upstanding on a hilltop after the surrounding rock has been broken down and removed.
Weathering
Process by which exposed rocks are broken down on the spot by the action of rain, frost, wind and other elements of weather.
Salt crystallization
Causes decomposition of rocks by solution of salt.
Exfoliation
When rocks heat up and cool down (contract) at nightime, stresses occur in outer layers casting the rock to peel.
Aggresivity
Ability of water to de solve calcium carbonate
