Wearing Down Earth’s Surface Chapter 1 Lesson 2. Mechanical Weathering.
Rates of weathering lesson 6
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Transcript of Rates of weathering lesson 6
RATES OF WEATHERI
NGLesson 6
Rates of weathering The speed at which rock are broken down.
This depends on several factors:ClimateRock CharactericsVegetation
CLIMATEChemical Weathering Physical Weathering
Most intense in hot and wet climate
Chemical reactions promotes by high temperatures
Heavy rainfall provides necessary moisture for the processes
E.g: Deep weathering profile and typical red soil in tropical climate reflect active oxidation
Particularly active in cold climates where frost shattering dominates
Also active in desert climates where insolation weathering or exfoliation dominates
Climatic conditions 1. Strong Chemical Weathering – Hot and
wet Temperature: 70C – 300C Rainfall : 1600 – 2500mm
2. Weak Chemical Weathering Temperature: -30C to -200C Rainfall : 0 – 900mm
3. Strong Physical Weathering Temperature: -50C to -100C Rainfall : 300 mm to 1300mm
4. Weak Physical Weathering Temperature: 00C to 90C Rainfall : 0 – 1700mm
Rock CharacteristicsDefine the term joints
and bedding planes.
Joints – fractures or cracks that run through rocks
Bedding planes – the junctions between
beds of sedimentary rocks
Permeability and porosityWhich of the following texture is easily
weathered?
VegetationPresence of vegetation promotes
weathering
Organic acids speed up hydrolysis
Moss cling to rock surface, holding water against them like a wet sponge encourage chemical weathering
At the same time protect a rock surface from temperature extreme which reduce physical weathering