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26 Cards in this Set
- Front
- Back
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what are the two types of weathering?
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Chemical and physical (also called mechanical)
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what is weathering? (definition)
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the physical breakdown and chemical alteration of rocks at or near the Earth's surface
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Chemical weathering
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the chemical transformation of a rock into one or more new compounds
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chemical weathering of feldspar
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CO2 in atmosphere dissolves in rainwater makes carbonic acid which converts feldspar into dissolved silica, K, and bicarbonate
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what is the importance of carbonates weathering?
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they are an important crustal rock. chemical weathering of carbonates is important in humid climates
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what is the relation between Bowen's Reaction series and chemical weathering?
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Minerals that crystallize high at high temperature on the series have trouble being unstable and susceptible to severe weathering
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what is physical (mechanical) weathering?
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physically breaking up a rock without altering its mineral composition
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what are the 4 types of physical weathering?
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fragmentation, exfoliation, spheroidal weathering, frost wedging
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Frost wedging
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the freeze-thaw cycle that occurs naturally between the cracks in many rocks that breaks up rocks as liquid water freezes and expands.
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which climates favor which type of weathering?
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humid, warm climates favor chemical weathering, whereas cold, dry climates have relatively more physical weathering
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Spheroidal weathering
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the gradual rounding of a rock's edges due to chemical weathering
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what is the definition of soil?
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it is a combination of mineral organics water and air. soils are the product of chemical and physical weathering
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what are the 5 factors that affect soil formation?
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Parent material (easily weathered material aids soil formation), time (thicker the soil the longer it took to develop), climate (most important: hot humid is best), plants and animals (vegetatoin defines soil types), and slope (bottom lands-thick and dark soils)
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what are the factors in soil texture?
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texture depends on grain size and distribution of particle and texture important b/c it controls ability to hold water
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Order of soil horizons in descending order
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O, A, E, B, C
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O Horizon
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consists mainly of organic material. top half consists of plant litter and other recognizable debris, but the bottom half is humus
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A Horizon
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mainly mineral in composition although can contain humus and other biological activity, up to 30% in some cases
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what is the topsoil?
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the first two horizons, the O and A horizons.
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E Horizon
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horizon with little organic material and light in color. also known as zone of leaching.
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B Horizon
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also known as the zone of accumulation for the particles present by eluviation through previous horizons. also known as the subsoil
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what is the solum?
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it is the 'true soil': horizons O, A, E, and B.
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C Horizon
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Variant of lowest level (unweathered parent material) as it is slowly preparing to become soil but is still a heavy resemblance to the parent.
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Three types of soil
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pedalfers, pedocals, and laterites
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Pedalfers
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-Al and Fe in soil (B Horizon)
-formed in mid-latitudes with moderate precipitation |
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Pedocals
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-Ca in soil
-Arid and semi-arid environment |
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Laterites
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-Not soluble minerals, just clay and Fe oxides
-Hot, tropical climates |
