Soil Formation

http://www.youtube.com/watch?v=bTzslvAD1Es

What is Soil?

• Loose covering of broken rock particles and humus (decaying organic matter)

• Found in nearly all regions of the Earth• Formed by chemical and physical weathering• Affected by climate• Four types

How Soil is Formed

• Requires 5 things:– parent material, topography, climate, organisms, time

• Creates soil horizons

Weathering

• Physical– Temperature, pressure

• Chemical– Water (hydrolysis), oxygen (oxidation), carbon

dioxide (carbonic acid), acid rain

Erosion

• Movement of weathered material from one location to another– By water, air, ice

Topography

Climate

• Cool, dry, sparse vegetation– Predominantly physical weathering

• Warm, wet, abundant vegetation– Increased chemical weathering

Global Soil Distribution

Polar Soil

• Form at high latitudes/elevations• Found in Greenland, Canada, Antarctica• Generally have good drainage• Very shallow

Temperate Soil

• Form in temperate areas • Found in the eastern US, Europe, eastern Asia,

southern Africa and South America• Wide variation - based on annual rainfall

amounts

Desert Soil

• Form in arid regions • Found in western US, northern Africa,

Australia, Middle East, parts of Russia & China• Can only support a limited amount of

vegetation

Tropical Soil

• Form in areas that have high temperatures & heavy rainfall

• Found in South America, central Africa, India, Indonesia

• Soil is generally very poor in nutrients

Geohazards

Geohazards• Landslides• Mudslides• Avalanches• Falling rock• Volcanoes• Earthquakes• Floods

Geohazard Protection