Geography Chapter Notes

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Chapter 15 Outline
* Soil is the relatively thin surface layer of Earth’s crust consisting of minerals and organic matter modified by natural actions like… * Weather
* Wind
* Water
* Organisms
* Soil is formed from parent material, rock that is slowly broken down or fragmented into smaller particles by… * Weathering Processes
* Chemical
* Physical
* Topography, a region’s surface features such as the presence or absence of mountains and valleys, is also involved in soil formation. * Soil Composition: soil is composed of 4 distinct parts, minerals that make up 45% of a soil. * Organic Material (5%)

* Water (25%)
* Air (25%)
* Mineral portion which comes from weathered rocks provides anchorage and pore space for air and water. * Age affects mineral composition
* Australia, South America, India have old infertile soil * Litter (dead leaves and branches on the soils surface)
* Humus: Black or dark brown organic material that remains after decomposition has occurred. * Illiviation: The deposition of leached material in the lower layers of soil * Soil Horizons:

* O-horizon (accumulation of plant litter)
* A-horizon (accumulation of organic matter of humus) * E-horizon (heavily leached)
* B-horizon (accumulation of clay and nutrient materials) * C-horizon (weathered pieces of rock)
* Solid Parent Material (bedrock)
* Soil Organisms:
* Ecosystem Services: maintaining soil fertility
* Castings: bits of soil that have passed through the gut of an earthworm are deposited at the soil’s surface. * Mycorrhizae: helps plants absorb adequate amounts of essential nutrient minerals. * Mycelium: fungal threadlike body

* Soil Texture refers to the relative proportions of different sized inorganic mineral particles of sand, silt, and clay. * Sand-largest soil particle
* Silt...
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