geomorphic processes Flashcards
what is weathering?
in a glacial areas some types of weathering are particular significant and therefore influence the formation of glacial landforms
uses heat energy to produce physically or chemically altered materials from surface or near surface rock
what is physical weathering?
The breakdown of rocks without chemical change. Usually, this is caused by abrasion.
what is freeze thaw weathering?
Water enters cracks/joints and expands by 10% when it freezes. In confined spaces this exerts pressure on the rock, causing it to split or pieces to break off, even in very resistant rocks
the more frequent the more effective the process will be
what is frost shattering?
at extremely low temps, water trapped in rock pores freezes and expands
this creates stress which disintegrates rock to small particles
what is pressure release?
when the weight of overlying ice in a glacier is lost due to melting, the underlying rock expands and fractures parallel to the surface
this is significant in the exposure of sub-surface rocks such as granite and is also known as dilation
parallel fracture sometimes called pseudo-bedding planes
what is chemical weathering?
decomposition of rock caused by chemical reactions between elements of the weather and some minerals within the rock.
may reduce the rock to its chemical constituents or alter the chemical and mineral composition of the rock
what do chemical weathering processes produce?
weak residue of different material that may then be easily removed by erosion or transportation processes
what does the temperature do to chemical reaction?
the rate of most chemical reactions are faster when the temperature is higher
where are most chemical weathering processes more effective?
in warm or hot climates and regions
how do some weathering processes effect the atmosphere?
when rocks are in contact with weakly acidic water
one issue with climate change and increasing levels of atmospheric CO2 is that rain and therefore ice is becoming more acidic
what is oxidation?
a chemical process that weathers certain types of rock and involves the absorption of oxygen from either the air or water by rock minerals
what is carbonation?
Rainwater absorbs CO2 and forms carbonic acid. The acid dissolves alkaline rocks such as chalk, creating calcium bicarbonate which is washed away in the solution.
is reversible
what is a solution?
the chemical weathering process by which rock minerals are dissolved
what is hydrolysis?
a chemical reaction between rock minerals and water
silicates combine with water producing secondary minerals such as clays
what is hydration?
water molecules added to rock minerals create new minerals of a larger volume
can cause surface flacking in many rocks, partly because some minerals also expand by about 0.5% during the chemical change as well because they absorb water