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114 Cards in this Set
- Front
- Back
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Element |
substance that cannot be broken down into another stable material (atoms) |
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Minerals |
solid, naturally occurring earth minerals with a crystal structure and definite chemical composition >4000 minerals formed by crystallisation |
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rocks |
solid, naturally occurring components in masses almost always composed of different combination of minerals |
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earths composition |
oxygen 46.6% silicon 27.72% aluminium 8.33% iron 5.00% calcium 3.63% sodium 2.83% and others |
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rare earth elements |
elements that are below 1% of the earths composition |
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rock types |
igneous metamorphic sedimentary below crust, 94% igneous/metamorphic on crust, 75% sedimentary |
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crystallisation
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formed by magma cooling if ejected to the surface, magma cools quickly and yields small crystals if cooled slowly, bigger crystals form |
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metamorphism |
heat and temperature causes metamorphism and creates new minerals |
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colour |
moderately useful diagnostic tool for minerals and rocks - moreso for darker ones very useful diagnostic tool for soils |
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lustre |
looks at minerals or rocks to determine: metallic/non-metallic glassy, vitreous, dull, pearly, resinous, waxy reflection of surface |
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streak |
use mineral/rock to scratch unglazed porcelain to determine internal colour (may vary from external colour) |
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cleavage |
observes cleavage planes breaks occur along these planes consider the cleavage planes relative to the crystal |
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fracture |
the way a crystal fractures when there are no cleavage planes |
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crystal form |
the way a crystal grows ie some minerals grow with flat sides |
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specific denisty |
density = mass/volume water has a DS of 1 does not measure the weight of minerals/rocks |
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magnetism |
observe if a mineral can be picked up, or if it is a magnet |
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reaction to HCl |
if a mineral or rock reacts with HCl, it has carbon good tool for diagnosis |
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flourescence |
observe if minerals glow under UV light occurs due to excitation of electrons |
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double refraction |
diagnostic tool of transparent mineral/rock may cause double-imagine of whatever is behind the rock |
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Silicates (and their structures) |
Two types ¨Light silicates¨ and ¨Dark silicates¨ named after their shade of colour characterised by atomic structure called a ¨silicon-oxygen tetrahedron¨ five silicate structures: 1) single tetrahedron = no cleavage 2) chains = two planes at right angles 3) double chains = two planes at 60° and 120° 4) sheets = one plane 5) three-dimensional networks = no cleavage mafic = simple orientation felsic = complex orientation |
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oxides |
metallic elements combined with oxygen has simple crystal structure and chemical composition |
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sulfides |
metallic or semi-metallic elements composed of sulphur |
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carbonates |
contains carbon abundant in earths crust mainly colourless, white or transparent but can be colourful |
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sulfates (sulphates) |
contains at least one metallic element and a sulfate is a widely varying group |
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phosphates |
metallic elements in combination with phosphate often brightly coloured often formed by alteration of iron, lead, copper and zinc sulfides exhibits clusters of altered and unaltered minerals in one specimen |
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halides |
contains a halogen element (Chlorine, flourine, iodine) many halides are weak, brittle or soft some are very soluble in water |
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native elements |
elemental minerals (does not contain any other element) gold, silver, plantium, diamond very rare |
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igneous rocks |
produced from the crystallisation of minerals from magma crystal size is bigger the slower magma cools |
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Geomorphological provinces in Australia |
Western Australian Shield very old diverse rock types tectonically stable moderate landform diversity Eastern Highlands young diverse rock types tectonically active diverse landforms Eastern Australian Basins mid-age common sedimentary rocks moderate tectonic activity flat landscapes |
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Magma |
originates deep within the earth stays below the earths surface cools more slowly, resulting in larger crystals magma that comes to the surface is lava |
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lava |
initially originates deep in the earth as magma erupts onto the surface through volcano or crack (fissure) tends to cool quickly, resulting in smaller crystals |
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texture |
the grain size in a mineral, rock or soil influenced by weathering or rate of cooling four types: 1) glassy = no visible grains 2) aphanitic = fine <1mm 3) phaneritic = coarse grain 1-10m 4) pegmatitic = very large crystals >2cm |
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porphyritic rocks |
a rock with a mixture of grain sizes due to a mixed cooling history |
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matrix |
finer crystals surrounding larger crystals mixed grain sizes imply an upward movement of magma from a hot, deep location to a shallower, cooler one |
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vesicles |
the holes in rocks formed from the gas bubbles in lava or magma very porous |
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pyroclastic |
pieces of rock and ash (scoria) ejected from a volcano and welded together by heat |
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felsic |
dominated by silicon and aluminium light coloured characteristic of continental crust form a stiff (viscous) magma |
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mafic |
contains ferromagnesium minerals usually dark in colour characteristic of earths ocean crust forms runny (low viscosity) lava |
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bowens reaction series |
shows order in which rocks crystallise from a magma lists order in which rocks melt with increasing temperature earlier formed minerals react with magma to form minerals lower in the series minerals become more complex as crystallisation proceeds certain minerals tend to occur together in igneous rocks minerals that ultimately form are controlled by the initial composition of magma two kinds: continuous and discontinuous |
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continuous reaction series |
felsic minerals on the bowen reaction series forms Ca plagioclase to Na Plagioclase |
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discontinuous reaction series |
mafic minerals on the bowen reaction series forms olivine to biotite |
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sedimentary rocks |
formed under pressure from accumulated sediment aka lithiphication sedimentary rocks usually deposited in layers, termed "beds" or "strata" a thick stratum of one kind of rock is called a formation three types: terrigenous biochemical/chemical organic |
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metamorphic |
rocks subjected to extreme pressure and temperature aka metamorphism the lithology of protolith sets the fundamental nature of the final metamorphic rock three agents of metamorphism: 1) heat 2) pressure 3) chemical |
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lithiphication |
"compacted by pressure and cemented" when buried, sediment is lithified to form sedimentary rocks at greater depths, sediment can be recrystallised to form metamorphic rocks |
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terrigenous (clastic) |
derived from weathering of preexisting rocks sediment has been transported and deposited subdivided according to particle size (texture) |
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biochemical/chemical |
divided by chemistry or formation 1) evaporates: forms from evaporation of water 2) carbonates: both chemical and biochemical processes 3) siliceous rock: dominated by silica (SiO2), commonly from silicia secreting organisms |
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organic sedimentary rocks |
derived from organic matter does not have minerals form coals differences in temperature and pressure affect how coals form four kinds of coal: 1) peat 2) ilignite 3) bituminous coal |
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protolith |
what a rock was originally before it undergoes change due to heat and pressure |
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heat affecting metamorphism |
regional metamorphism is when the heat affects a whole region
increases temp with depth contact metamorphism affects only the rock on contact intrusions bake surrounding rocks lava can bake surface rocks |
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pressure affecting metamorphism |
depth increases pressure in regional metamorphism tectonic pressure at plate boundaries affects regional metamorphism fault zone pressure increases in pressure in fault zones against dynamic metamorphism |
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chemicals affecting metamorphism |
hydrothermal solutions (terrestrial) new minerals crystallise from hot hydrothermal solutions marine hydrothermal solutions are injected into oceans, producing sulfide minerals and copper precipitates |
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changes in texture due to metamorphism |
changes in texture can be due to metamorphism, resulting in three groupings: 1) folation: alignment in sheet like minerals 2) lineation: alignment of elongated, rod like minerals 3) non-foliated: equi-dimensional grains form a mosaic after metamorphism |
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weathering |
the physical disintegration and chemical decomposition of rocks, sediments and soils
three types of weathering: 1) physical weathering 2) chemical weathering 3) biotic weathering |
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Bioclimatic factors of weathering |
Rainfall and Temperature are the direct factors which influence weathering High rainfall and temperature are optimal conditions for chemical weathering as temperature decreases, the general weathering rate decreases |
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Biotic weathering |
an indirect weathering effect through vegetation the direct effect is through rain and temperature |
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physical weathering |
Breaking up of rocks, soils and sediments into smaller grain sizes Some examples of this are: 1) heating and cooling 2) wetting and drying 3) freezing and thawing Physical weathering is often a precursor to chemical weathering Physical weathering decreases grain size and increases surface area Three subtypes of physical weathering are: 1) Granular Disintegration 2) Exfoliation 3) Ice Crystallisation |
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Granular Disintegration |
The differential expansion and contraction of multi-mineralic rocks builds up internal stresses felsic minerals are more resistant to granular disintegration mafic minerals undergo expansion and contraction more readily |
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Exfoliation |
Onion peel weathering The expansion and contraction due to temperature is more effective on the surface layer Therefore the surface layer separates itself off the main mass |
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Ice Crystallisation |
Has a freeze-thaw effect When frozen, there is an increased volume buildup inside the rocks When thawed, they return to normal size Salt Crystallisation has a similar affect as freezing When salt crystallises it expands and stresses the rock |
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Chemical Weathering |
Chemical weathering may create new minerals It reduces the size of existing minerals It creates Secondary Minerals and leaves behind residual minerals Two kinds of chemical weathering: 1) Physical effects of ion exchange 2) Effects of ion excange upon net electrical charge |
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secondary minerals & residual minerals |
Secondary minerals are created as a new mineral via chemical weathering (ie Fe/Al oxides) Residual minerals are the minerals that are left behind (often smaller) after the weathering process has occured |
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Physical effects of chemical weathering |
Physical effects of chemical weathering are due to ion exchanges
The exchange of a larger ion in a tetrahedral causes distortion Exchange of smaller ions causes collapse This is why tetrahedrals are more affected by weathering |
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Effects of ion exchange upon net electrical charge |
An example of ion exchange upon electrical charge is when acid rain dissolves limestone via hydrolysis Or when metals are acted upon by water, it rusts (oxidation). |
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Products of weathering |
Weathering is responsible for creations of landforms and soils Regolith and Soils are the result of weathering |
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Landforms resulting from weathering |
Four kinds of unique landforms as a result of weathering: 1) Tors and Residual Bolders 2) Scree Slopes 3) Karst Landscapes 4) Inselbergs (Mesas) |
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Tors and Residual Bolders |
Are what are left behind when the rock around it is weathered away Tors and Residual Bolders than the rocks surrounding it |
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Scree Slopes |
Product of weathering in alpine or polar areas A verticle cliff face gets worn down and accumulates a slope of sediment making a "ramp" The slope angle is a factor of the regolith size |
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Karst Landscapes |
Karst Landscapes are primarily limestone When it acid rains, the limestone is dissolved This creates unique landscapes (ie sinkholes) |
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Inselbergs (Mesa) |
An example of this is Uluru (sandstone) However most are granite and very large residual rocks They are a piece of large rock that has been exposed by the lowering of the landscape via weathering A Mesa is residual ground that remains as the surrounding landscape lowers In Australia , there are Mesa's which remain as a relic from the times of when Australia was a Tropical Continent with rainforests. This ground was oxidised and was hardened, and still remains today. |
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Soils |
Thin layer of unconsolidated material Four sections: 1) Mineral fraction 2) Organic fraction 3) Soil water 4) Soil air |
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Soil profile |
A vertical section of a soil extending from the surface to the underlying rock |
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Parent rock |
The underlying rock from which soil has developed |
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Soil horizon |
A sub horizontal layer within a soil profile Possess relatively uniform characteristics |
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Horizons |
O-horizon - Organic matter A-horizon - Mineral and organic matter B-horizon - Clay, Fe, Al, O-matter, or a mix or all C-horizon - Consolidated or unconsolidated apparently unaffected by pedogenesis D-horizon - Horizons below A/B profile but are not C/R horizons R-horizon - Underlying rock |
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Mottling |
The result of soil becoming waterlogged due to bad drainage |
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Regolith |
A layer that contains: Residual minerals Secondary minerals unweathered/partially weathered primary minerals Rock fragments |
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Particle size distribution |
A range of particle size within a soil Soil contains a record of its history and if its related to the underlying rock |
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Soil structure |
can characterise soil structure by shape or size it shows how soil erosion may proceed for a specific soil aggregates influence how soil is transported |
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aggregate |
particles stuck together by: electric charge organic nets polysaccharide gums and other cement allows soils to hold water allows air to enter the soil and stop it from being waterlogged |
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organic matter |
has an influence on: 1) soil colour 2) soil structure 3) water holding capacity 4) nutrient status affects aggregation affects water holding capacity water is attached to the surface of organic molecules water stores nutrients soils with water tend to has nutrients |
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Soil water |
Not free flowing has a high ion concentration gaps between particles are called micropores (small), pores (big) water and air diffused through the pores water absorption rate dependant on porosity three types: 1) hydroscopic water 2) capillary water 3) gravitational water |
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hydroscopic water |
help closest to particles via adhesion pF 4.2-7 wilting point - pF 4.2 always hydroscopic water in humid environments |
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capillary water |
cohesive pF 2.4-4.2 field capacity - pF 2.5 (optimal/average) capillary water is stuck to hydroscopic water comes and goes depending on rain/temp |
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gravitational water |
water pulled downwards by gravity pF <2.5 usually ends up in water table |
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water storage rates |
affected by soil water affected by particle size, structure, O. matter storage rates are how much hydroscopic and capillary water is held in the soil water is stored in the pores between aggregates air can dry out water from pores over time |
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soil water |
infiltration is higher when surface is dry influenced by steepness of slope lateral aluvation occurs at horizon boundaries, and horizon/rock boundaries mottling is when water doesn't drain, soil becomes washed out soil air can dry out soil water it can diffuse into the soil soil water usually holds more strongly to micropores - less space to airate |
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soil air |
repriciporical of soil water water and soil cannot share the same space in soils larger pore spaces usually has more air due to more space for airation soil air not influenced by gravity only indirectly affected by slope angel due to influence of water by slope angle |
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pedogenesis |
the process of soil formation three factors: 1) soil production process 1.1) humification 1.2) weathering 2) soil distribution process 2.1) exchange 2.2) translocation processes 2.3) aggregation 3) surface transport processes 3.1) colluvial processes 3.2) alluvial processes 3.3) aeolian processes |
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soil production processes 1) humification 2) weathering |
1) humification top down weathering effect produces humus, releases ions can be changed by soil management 2) weathering bottom up effect produces clays, releases ions not affected by soil management |
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soil distribution processes 1) exchange 2) translocation processes 3) aggregation |
1) exchange the ion exchange scale Na K Ca Mg Si Fe Al Mn Ti Easy to exchange -> hard this is the movement downwards of ions through the profile into groundwater, and out of the catchment 2) translocation processes downwards - leaching upwards - evaporation driven laterally - movement at horizon boundaries leeching susceptibility scale Si Fe Al Ca Mn K Na low -> high 3) aggregation opposite of exchange stabilises soil influenced by electric charge on particle surfaces increases sotrage of nutrients decreases translocation |
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soil salinity |
when surface temperature of soils is hot it pulls water upwards via evaporation this brings Na and K to the surface and causes salinity |
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surface transport processes 1) colluvial processes 2) alluvial processes 3) aeolian processes |
occurs a lot in Australia 1) colluvial processes slope processes - overland flow or mass movement overland flow due to water mass movement directly influenced by gravity 2) alluvial processes movement of nutrients and sediment in river particles collect near river edge 3) aeolian processes movement of soil material over wind systems |
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Infiltration |
Infiltration influenced by: 1) rainfall total (mm/yr) 2) rainfall intensity (mm/hr) Also influenced by O-horizon storage of water, by water uptake of plants, and by whether or not soil surface is dry Other influencing factors are soil characteristics: Soil texture, structure, surface condition |
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Overland flow |
When soil surface is wet, runoff occurs Overland flow can occur as: 1) sheet flow 2) rills 3) gullies 4) through flow (tunnelling/piping) |
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Sheet flow (sheet wash) |
entrainment and some detachment sheetwash is the movement of water down a slope near laminar flow thin flow depth entrains and detaches soil operates and affects a large area |
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rill wash (rill flow) |
when sheetwash increases in intensity, it becomes rill wash turbulent flow greater flow depth additional process - rill bank erosion high sediment concentration smaller surface area occurs when slopes get steep |
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gully erosion |
when rill erosion becomes more turbulent small surface area large flow depth very high sediment concentration |
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rainfall erosivity |
rainfall erosivity is the function of: 1) rainfall intensity 2) rainfall totals 3) rainfall drop size summer rain has large drop sizes due to more thunderstorms winter rain tends to be drizzle and less erosive |
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erosion due to particle size |
1) fine soils are more erodible (opposite for wind erodibility) 2) aggregation may increase erodibility (if its fine) or decrease erodibility (if its coarse) 3) organic matter decreases erodibility 4) salinity (Na) - increases erodibility 5) horizonation - may increase decrease erodibility 6) surface condition - crusting decreases erodibility |
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soil erosion 1) rainfall 2) particle size 3) slope length 4) vegetation cover 5) conservation practice |
1) rainfall - larger drops cause erosion 2) particle size - particle size, O matter, salinity, horizonation, surface condition affect 3) slope length - length of slope determines amount of catchment up slope to eroside sediment 4) vegetation cover - trees offer some protection, grasses offer more 5) conservation practice - man-made factor increasing vegetation cover and shortening slope length with banks |
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cantena |
a regular repetition of a certain sequence of soil profiles in a certain topography Australia and Africa share cantenas the cantena is a unifying concept between soil science and geomorphology drainage can influence the cantena, indirect relationship with the water table |
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factors that change soil characteristics (3) |
1) soil drainage process 2) slopewash process 3) time |
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S = f (Cl, O, R, P, T) |
s - soil formation cl - climate o - organisms r - relief/topography p - parent rock t - time |
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Five processes of soil formation |
1) podzolisation 2) ferrallitisation 3) calcification 4) salinisation 5) surface transport, processes-aeolian transport |
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podzolisation |
podosols in australia weathering reasonably active humification limited occurs in coastal regions light coloured translocation/exchange active (lots of rainfall) Na, K, Ca are drained out from rain poor aggregation undergoes alluvial translocation |
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ferralitisation |
ferrosols in australia rich, red soils weathering of basalt rocks humification/weathering active much organic matter, very fertile alluviation can work, but due to high aggregation and O-matter, it can hold its nutrients allows water to pass freely/be stored/airate not affected by climate |
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calcification |
vertosols in Australia best australian soil humification very rapid savannah soil in eastern australia weathering results in unique characteristics: shrinks when dry, swells when wet dark coloured formed in subtropical-humid environs |
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salinisation |
sodosols in australia is a bad thing due to low rainfall, low ion exchange rate downwards mobile ions accumulate near the surface Na, K reduced alluviation also reduces ions being held down by water removal of vegetation raises water table agriculture irrigation also raises water table occurs when Aus used to be under the ocean |
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surface transport - process aeolian salination |
soils formed with aeolian saltation (dune sand) deposits dust storms transport sand out of desert inland river systems taken sand in land each time the process occurs, sand becomes finer black soils in eastern Aus has dust deposits, increasing fertility |
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aeolian geomorphic processes |
atmospheric processes air is less viscous than water creates the effects of creep, saltation and suspension the major environmental controls of wind erosion: Er = f (Cw, Cv, V, R, E, K) Er - wind erosion rate Cw - climate (erosivity) Cv - climate (erodibility) V - vegetation R - surface roughness F - fetch K - soil erodibility |
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creep, saltation, suspension |
creep is the rolling of course sediments saltation is the bouncing of finer sediment suspension is when particles are held in air/water these three processes can occur in air and water in water their is a solution load, which is how much sediment it can carry air does not have this |
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Er = f (Cw, Cv, V, R, E, K) Er - wind erosion rate Cw - climate (erosivity) Cv - climate (erodibility) V - vegetation R - surface roughness F - fetch K - soil erodibility |
Er - wind erosion rate -hard to measure -need to use complex tools (wind vane samplers) Cw - climate (erosivity) -stronger the wind, more erosive it is >16km/hr wind is erosive to most soils Cv - climate (erodibility) -rainfall influences vegetation/soil moisture dry soils/covered soils are less vulnerable V - vegetation -protects the soil with non-erodible roughness -forests offer better protection against wind than grass -the inverse is true for water R - surface roughness -two kinds of roughness: 1) non erodible - trees/boulders - lowers wind erosion rate 2) erodible - can be worn out - increases wind erosion rate F - fetch -fetch is the distance of uninterrupted wind flow down-wind -farmers grow shelter-belts to break wind flow K - soil erodibility -sand most erodible, clay/loam the least -aggregation of soils plays a roll -crusted surfaces protect against erosion, but less so than vegetation |
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impact threshold |
impact threshold is the speed at which wind or water can begin eroding soil |
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wind velocity threshold |
the speed at which wind needs to blow to erode a particular soil |
