Rick's Cafe in Jamaica Keith Fairbrother Erosion Door County, WI Lizzy Schneider.
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Transcript of Rick's Cafe in Jamaica Keith Fairbrother Erosion Door County, WI Lizzy Schneider.
Rick's Cafe in Jamaica
Keith Fairbrother
Erosion Door County, WILizzy Schneider
Erosion Timna Valley, IsraelNaamah Azoulay
CHEMICAL WEATHERINGDISSOLUTION
Water removes ions or ion groups from a rock ormineral and carries them away.
Precipitate later when water evaporates.Due to the bipolar nature of water molecules,
ions become dissolved and are transported insolution.
WEATHERING and the BREAKDOWN of ROCKS
CHEMICAL WEATHERING
DISSOLUTION
HaliteNa+ is attracted to OH- side of water moleculesCl- is attracted to the H+ side of water molecules
Water can also react with another compound to form an acid.
H2O + CO2 H2CO3 (Carbonic acid)
The acid can then decompose minerals.
H2CO3 + CaCO3 Ca+2 + 2HCO3- (Bicarbonate)
Removed by erosion
WEATHERING and the BREAKDOWN of ROCKS
Calcite
CHEMICAL WEATHERING
DISSOLUTION
Dissolution is the process by which caves are formed.Calcite is dissolved, Ca+2 and HCO3
- end up in theocean.
Then removed from the ocean by marine organismsin the production of skeletal material.
WEATHERING and the BREAKDOWN of ROCKS
CHEMICAL WEATHERING
OXIDATIONPositive ions in minerals combine with oxygen to
produce oxides.
4Fe+3 + 3O2 2Fe2O3 (hematite)
If the reaction takes place in water, limonite (FeOOH) is produced.
Collectively called RUST.
WEATHERING and the BREAKDOWN of ROCKS
CHEMICAL WEATHERING
OXIDATION
WEATHERING and the BREAKDOWN of ROCKS
Also affects other metals such as copper.
CHEMICAL WEATHERING
OXIDATION
WEATHERING and the BREAKDOWN of ROCKS
Oxidation has the same result with iron-rich rocksand minerals.
Affects olivine, pyroxenes, amphiboles, gabbrosand basalts.
CHEMICAL WEATHERING
HYDROLYSIS
WEATHERING and the BREAKDOWN of ROCKS
H+ and OH- ions in water displace other ions in a mineral structure producing a new mineral.
Feldspars are readily changed by hydrolysis.
2KAlSi3O8 + 2H+ + 9H2O
Al2Si2O5(OH)4 + 4H4SiO4 + 2K+
OrthoclaseFeldspar
Kaolinite SilicicAcid
Hydrolysis of orthoclase, other feldspars and maficminerals produces clays and clay minerals.
Clays become incorporated in soils or wash to thesea by erosion.
Dissolved materials produced can cement sedimentary grains
Or, be utilized by plants (K+).
CHEMICAL WEATHERING
HYDROLYSIS
WEATHERING and the BREAKDOWN of ROCKS
So……
What are the factors that influence
CHEMICAL WEATHERING?
FACTORS THAT INFLUENCE CHEMICAL WEATHERING
WEATHERING and the BREAKDOWN of ROCKS
CLIMATE
Water drives all three reactions discussed.Heat also speeds reactions.Warm, humid climates are most suitable for chemical
weathering reactions.Warm, humid climates also tend to have more plants.When plants die, decomposition increases the
production of organic acids and increaseschemical weathering.
FACTORS THAT INFLUENCE CHEMICAL WEATHERING
WEATHERING and the BREAKDOWN of ROCKS
LIVING ORGANISMSMix up soil exposing more material to surface for
weathering reactions.
FACTORS THAT INFLUENCE CHEMICAL WEATHERING
WEATHERING and the BREAKDOWN of ROCKS
TIME
The longer a rock or mineral is exposed to weatheringthe more weathering takes place.
FACTORS THAT INFLUENCE CHEMICAL WEATHERING
WEATHERING and the BREAKDOWN of ROCKS
MINERAL COMPOSITION
The effect of chemical weathering in rocks is relatedto the stability of the minerals in the rock.
Since most rock-forming minerals are silicates, the strength of the bonds between the silica tetrahedra influences how they are weathered.
The more silicon-oxygen bonds between thetetrahedra, the more resistant to weathering is the mineral.
WEATHERING and the BREAKDOWN of ROCKS
PRODUCTS OF CHEMICAL WEATHERING
WEATHERING and the BREAKDOWN of ROCKS
Or….What’s left after dissolution, oxidation andhydrolysis.
Clay Minerals Produced by hydration of feldspars and
mafic minerals (olivine, pyroxenes, andamphiboles).
PRODUCTS OF CHEMICAL WEATHERING
WEATHERING and the BREAKDOWN of ROCKS
CLAY MINERALSType of clay formed depends on climatic conditions
during hydrolysis.Kaolinite forms in warm, humid climates.Smectite forms in cool, dry climates.
Uses of clay minerals:
Agricultural fertilizers Lubricants in oil drillingBricks and cement Paper productionCat litter KaopectateFiltering impurities from beer and wine
PRODUCTS OF CHEMICAL WEATHERING
WEATHERING and the BREAKDOWN of ROCKS
METAL ORES
AluminumForms from chemical weathering of feldspar-
rich rocks in warm, humid climates.Leads to the concentration of aluminum in
Bauxite (Al2O3 . nH2O).
PRODUCTS OF CHEMICAL WEATHERING
WEATHERING and the BREAKDOWN of ROCKS
SPHERIODAL WEATHERING
Mechanical weathering breaks up rocks into smallerpieces.
Chemical weathering rounds off corners.
SOILS AND SOIL FORMATION
WEATHERING and the BREAKDOWN of ROCKS
Mechanical and chemical weathering of sedimentand pre-existing bedrock below producesREGOLITH.
REGOLITH is all the material above the bedrock.
SOIL is the upper part (up to a few meters) of regolith that supports plant life.
Soil contains both mineral and organic matter (decaying vegetation).
Soil also contains air and water.
SOILS AND SOIL FORMATION
WEATHERING and the BREAKDOWN of ROCKS
REGOLITH
REGOLITH
SOILS AND SOIL FORMATION
WEATHERING and the BREAKDOWN of ROCKS
SOIL
SOIL
INFLUENCES ON SOIL FORMATION
WEATHERING and the BREAKDOWN of ROCKS
PARENT MATERIAL
The bedrock or sediment from which soil forms.Influences nutrient richness of the soil.
Quartz-rich sandstoneBasalt
INFLUENCES ON SOIL FORMATION
WEATHERING and the BREAKDOWN of ROCKS
CLIMATE
Precipitation and temperature influence soil formation.Influences the rate of chemical weathering.Also influences plant growth.Soil formation is most rapid in warm, moist climates.
INFLUENCES ON SOIL FORMATION
WEATHERING and the BREAKDOWN of ROCKS
TOPOGRAPHY
Physical features of the landscape.Influences the availability of water.Influences the rate of soil accumulation.Steep slope vs. gentle slope
INFLUENCES ON SOIL FORMATION
WEATHERING and the BREAKDOWN of ROCKS
VEGETATION
Contributes organic matter to soil.Produces CO2 and O2 involved in chemical weathering.Plants contribute H+ that helps weather soils.
Aids in hydrolysisDegrades feldspars and other mineralsinto clay minerals.
Clays increase nutrient supply to plants.
INFLUENCES ON SOIL FORMATION
WEATHERING and the BREAKDOWN of ROCKS
TIME
The longer the time Earth materials are weathered, the thicker the soil produced.