21
Weathering and Erosion
What do volcanoes and tectonic activity do to the surface of the Earth?
Mt. Everest is increasing in height by approximately 2 inches each year.
Build it up!
Mechanical Weathering
The breaking down of rock by mechanical means. The smaller pieces retain the characteristics of the larger piece.
• Ice Wedging• Organic Activity• Abrasion
Organic Activity
Chemical Weathering
Chemical reactions alter the internal structure of rock breaking it down.
• Hydrolysis• Carbonation• Oxidation• Acid precipitation
Hydrolysis: Chemical reaction between minerals and water
Carbonation: Carbon dioxide and water combine to form a weak acid (carbonic acid)
Oxidation: When elements (especially metals) combine with oxygen
Acid Precipitation: Oxides of sulfur and nitrogen dissolved in water form acids (usually produced in industrial areas)
What factors affect the rate of weathering?
Factors that Effect Rates of Weathering?
• Rock Composition
Sandstone: Moh’s hardness of 5
Quartz: Moh’s hardness of 7
More Factors
• Amount of Exposure • Climate – what climate conditions or combination of conditions increase weathering?
• Warm moist climates• Variable temperatures
for freezing and thawing
SoilThe top 6 elements in the human body are
• Nitrogen• Carbon• Hydrogen• Oxygen• Phosphorous• Sulfur
Where do we get them from?
Soil is a combination of…
• Mineral matter• Organic matter• Water • Air
Humus = Organic Matter
Decayed plant & animal matter provides nutrients and helps with water retention
Not to be confused with Hummus
What influences the rate of soil production?
• Time• Climate• Plants & Animals• Slope
Soil,It’s Impoprtant!
soil
O = Organic LayerA = TopsoilB = SubsoilC = Parent Material
Below that = bedrock
Soil texture is important for…
• Agriculture• Engineering
Soil Texture TriangleThe rock material in soil is made up of• Clay (<0.002mm)
• Silt (0.002 – 0.6 mm)
• Sand (0.6 mm – 2 mm)
