Weathering Processes Affecting River Valleys

Question 0

Biological weathering

Answer 0

Involves both mechanical impacts e.g. Growth of roots and chemical impacts e.g. Release of organic acids

BIOLOGICAL

Question 1

Freeze thaw

Answer 1

Water in joints freezes, expands by 10% and exerts pressure up to 2100kg/cm(2)

MECHANICAL

Question 2

carbonation solution

Answer 2

occurs on rocks with calcium carbonate. rainfall and dissolved carbon dioxide form weak carbonic acid. calcium carbonate reacts with acid water and forms calcium bicarbonate which is soluble and roved by percolating water

CHEMICAL

Question 3

exfoliation

Answer 3

found in hot deserts where there is a large diurnal temperature range. rocks heat up by day and contract by night. rock=poor heat conductor so stresses take place only on outer layers and cause peeling or exfoliation to occur.

MECHANICAL

Question 4

pressure release

Answer 4

process where overlying rocks removed by erosion cause underlying ones to expand and fracture parallel to the surface

MECHANICAL

Question 5

hydration

Answer 5

certain minerals absorb water; expand and change; for change and anhydrate is changed to gypsum during hydration

CHEMICAL

Question 6

oxidation

Answer 6

occurs when iron compounds react with oxygen to produce a reddish/brown coating

CHEMICAL

Question 7

decomposition

Answer 7

chemical weathering of rocks creating new materials

CHEMICAL

Question 8

in situ

Answer 8

on the spot without lateral movement

Question 9

disintergration

Answer 9

mechanical weathering of rocks resulting in smaller fragments of the same type