Weathering Flashcards
weathering
breakdown and/ or decay of rock on, or near the Earths surface
denudation
the wearing away of land over time by the action of weathering and erosion
endogenic + exogenic processes form the Earth landscape
endogenic = tectonic forces
exogenic = refers to weathering and erosive forces
3 main categories of weathering
physical (fragmentation of rock), biological and chemical (materials chemically altered or dissolved)
key terms for weathering
regolith - weathered bedrock, loose and broke up and icludes all forms of rocks waste
soil - thon layer of unconsolidated material at the earths surface that can support growth of plants
erosion - the removal and transport of material including rock, regolith and soil
types of physical weathering
organic action insolation pressure release crystal growth dessication
organic action
breaking up by roots
insolation
alternate heating of rocks by the sun during the day and night. e.g. hot deserts
pressure-release
pressure release from removal of overlying rocks.
crystal growth
salts in solution enter joints or pores of rock. crystal grows and breaks up rock. common around coasts or deserts
dessication/ wetting and drying
partially wetted and then dried
expands when wetted and contracts on drying. coastal areas
types of chemical weathering
hydrolysis hydration solution oxidation chelation carbonation
hydrolysis
most common. carbonic acid releases hydrogen ions enabling them to react. disintegrates material.
common in rocks containing feldspar i.e. granite
hydration
leads to granular disintergration and exfoliation.
when minerals absorb water into their crystal structure which can cause chemical changes - causes rocks to swell
e.g. anhydrate, a form of calcium sulphate absorbs water to become gypsum
solution
some soluble rocks require no chemical reaction to dissolve
