Chapter 16 E3 - Weathering Flashcards
the disintegration and decomposition of material at or near the surface
weathering
the transfer of rock material downslope under the influence of gravity
mass wasting
the incorporation and transportation of material by a mobile agent, usually water, wind, or ice
erosion
two kinds of weathering
mechanical weathering and chemical weathering
breaking of rocks into smaller pieces by physical processes
mechanical weathering
alters the internal structures of minerals by removing or adding elements
chemical weathering
_____ and _____ are the most crucial weathering factors
temperature and moisture
chemical weathering is most effective in areas of _____ temperatures and ____ moisture
warm
abundant
the three main mechanical weathering processes
frost wedging, unloading, and biological activity
repeated daily heating and cooling of rock causes fractures (heat expands and cool contracts) the release of overburden and increased temperature can cause pop ups
exfoliation
advanced mechanical weathering aids chemical weathering by increasing the
surfacea area
the most important agent in chemical weathering
water because oxygen dissolved in water oxidizes materials and CO2 dissolved in water forms carbonic acid
four types of chemical weathering
dissolution, oxidation, hydrolysis, and reductive dissolution
chemical weathering of granite
potassium feldspar forms clay minerals, soluble salt, and silica in solution; quartz remains mostly unaltered
weathering of most silicate minerals besides quartz produces
insoluble iron oxides and/or clay minerals
oxygen combines with iron bearing silicate minerals (like olivine, pyroxene, amphibole, and biotite) causing rusting
oxidation
red means
iron
caused by chemical weathering of jointed rocks where those rocks form roughly spherical shapes
spheroidal weathering
a speed control for weathering
chemical stability
caused by variations in composition
differential weathering
concentrates metals into economical deposits
secondary enrichment
two ways to have secondary enrichment
removing undesired material from the decomposing rock, leaving the desired elements behind; desired elements are carried to lower zones and deposited; translocation and transformation
controls on soil formation
parent material: residual soil and transported soil; and time: amount of time to evolve varies for different soils; climate, slope, and plants and animals
_____ slopes often have poorly developed soils
steep
refers to the proportions of different particle sizes
texture
large to small textures
sand (largest), silt, clay
a mixture of all three size textures and is best suited for plant life
loam
soil forming processes operate from the
surface downward
zones or layers of soil
horizons
horizons in temperate regions
O-organic matter A-organic and mineral matter E-little organic matter B-zone of accumulation C-partially altered parent material
soil profile in a temperate climate; humus and leached soil; some iron and aluminum oxides precipitated, all soluble materials leached away; granite bedrock
pedalfer
soil profile in a wet climate; thin or absent humus; thick masses of insoluble iron and aluminum oxides; occasional quartz; thin leached zone; mafic igneous bedrock
laterite
soil profile in a dry climate; humus and leached soil; calcium carbonate pellets and nodules precipitated; sandstone, shale, and limestone bedrock
pedocal
recycling of earth materials
soil erosion
natural rates of erosion depend on
soil characteristics, climate, slope, and type of vegetation
