lecture 5 Flashcards
what is weathering?
breaking down of rock into fragments
what s erosion?
when weathering and transportation takes place
what are the two types of weathering ?
physical and chemical
what is physical weathering?
breakdown of rock without change in mineral- residual soil is produced
what is residual soil?
soil that was made where it exists now
what are the processes of physical weathering?
temperature, moisture, freeze-thaw, crystallisation, vegetation, pressure relief
define crystallisation, vegetation and pressure relief
crystallisation: evaporation of groundwater
vegetation: root growth
pressure relief: the taking off of soil lying above mineral (overburden removal)
what is chemical weathering?
chemical breakdown of rock which changes the mineral
Why are the main products of weathering clay and quartz minerals?
because they are resistant to chemical weathering
what the chemical weathering processes?
solution- mineral dissolved in water
oxidation- with oxygen
hydrolisis- with water (where water in not broken down (hydration))
what is the hydrolysis reaction equation?
silica mineral+carbon dioxide+water = clay+soluble+salt +sand
why is special about limestone when it comes to its hydrolysis reaction
it produces calcium bicardonate which dissolves in water
what does the rate of weathering depend on?
environmental factors
“parent” material
structure
different means of soil transportation
water
ice
wind: (loess)
gravity
what is soil creep?
downslope movement of soil
