chapter 2 Flashcards
weathering includes
destruction and synthesis
new minerals form from
minor chemical alterations or complete chemical breakdown of original mineral
physical weathering (disintergreation)is the
making of small fragments with same composition of orignal rock
soil formation is stimulated by
climate and living organisms acting on parent materials over periods of time and under modifying influence of topography
signs that soil formation is happening
accumulation of organic matter in upper horizons,
downward movement of soluble ions,
synthesis and downward movement of clays,
development of soil structure
4 process of soil formation
gains, losses, transformations, translocations
erosion allows us to
get new parent material
erosion is
the lateral movement of materials downslope due to gravity wind and water
What is the first Weathering processes and state
Parent material, the initial state of system
What is the second Weathering processes and stateWhat is the first Weathering processes and state
the intermediate states, soil formation
what is the final Weathering processes and state
mature soil, the final state
Physical weathering
or mechanical weathering, the breaking of rocks into smaller particles (soils) without any change in chemical composition
chemical weathering
the process by which rocks are decomposed, dissolved, or loosened by chemical processes to form residual material
physical weathering is mainly a result of
changes in temperature, pressure, abriasian by water wind ice
evidence of chemical weathering
change in color due to dexos, depletion of original materials, alteration of minerals, neoformation of FE, changes in chem
physical weathering most ACTIVE IN WHAT ENVIORNMENT
very cold or dry
chemical weathering takes place
in wet and hot climates
what are the factors that influence soil formation
parent material, climate, biota, topography, time
How are soil horizons made?
by weathering
soil is made up of…
breakdown products of weathering + organic matter
What allows us to get new parent material
erosion
erosion
movement of materials downslope due to gravity, wind, water
what is the first part of weathering process
parent material, the initial state of system
what is the second part of weathering process
intermediate states, or soil formation
what is the third part of weathering process
mature soil, final state of system
physical weathering is
breaking down of rocks into smaller particles (soils) without any change in the chemical composition of the rock
Biogeochemical weathering (chemical weathering)
rocks being decomposed, dissolved, loosened by chemical processes to form residual material
In physical weathering, do the smaller fragments have the same composition as the original rock?
yes
physical weathering can be caused by
temperature, pressure, abrasian by water, wind ice
biogeochemical weathering
the breakdown of primary minerals and generation of secondary minerals
evidence of biogeochemical weathering
change in color
depletion of original minerals
alteration of original clay minerals
changes in major element chemistry
changes in chemistry of water flowing through the soil
biogeochemical breakdown is enhanced by
hydrolysis
hydration
complexation
oxidation-reduction
carbonation
hydrolysis
destruction of a mineral by reaction of H and OH ions in water
hydration
chemical combining of mineral with water molecules
complexation
ion or molecule binds to central metal
oxidation reduction
loss or gain of elections
carbonation
dissolution of co2 in water/solution
which weathering type is in cold and dry env. mostly
physical
what time of climate is chemical weathering most intense
wet and hot climates
What factors influence soil formation
parent material, climate, biota, topography, time
How do the two weathering methods work together?
physical weathering leads to increase of surface area for chemical weathering
What is parent material
the starting point for soil formation
igneous
formed from molten lava
sedimentary
formed when weathering products released from older rocks eventually form new rock
metamorphic
formed from older parent rock under heat or pressure in earths interior
darker minerals form…
soils faster and more nutrients
what mineral is most resistant to weathering
quartz
what primary mineral is least resistant to weathering
olivine
minerals
collection of elements with definite chemical composition and crystal structure
rocks
collection of one or more minerals
classification of parent material
by type of rock
by mode of placement
what are the two modes of placement in classification of parent material
residual and transporter
residual mode of placement
formed in place from native rock
transported by mode of placement
move by water ice wind or gravity
For every 10C rise in tempt. the rates of biochemical rections
double
high rainfall and high temperatures means
strong weathering
low rain fall high temp means
little weathering
low temp. mid rain fall means
strong weathering
does natural vegetation have effect on soil
yas
what is the effect of cultivation on soils
surface layers mixed by tillage, fast transformation of slil characteristics
Aspect
where you face the sun and how long
