Earth & Soil

Earth: Formed 4.6 Billion Years ago. Three section: 1. Biosphere: All life on land and water 2. Hydrosphere: All forms of water. 3. Internal Structure: Crust Mantle Core

Lithosphere Crust and Upper Mantle Creates movable plates on the surface of Earth

Plate Tectonics Seafloor spreading along the plate boundary

What happens where the plates come together ________

Rock Cycle Fossils Ex. Basalt Granite

SOIL / Not Dirt!!! Thin layer on top of most of the earth land surface

Soil is composed of three main ingredients 1. Minerals & organic materials 2. Air 3. Water

Soil Profile

Soil Composition Clay: Very fine particles. Low permeability. Soil can become water logged Silt: Fine Sedimentary material. Loam: Mixture of Clay, silt, sand and *Humus. Sand: Medium size Sedimentary material. Water flows through easily. Gravel: Course sedimentary material. Small rocks *Humus: Dark organic matter from decomposition.

USDA Soil Texture Chart

Soil Erosion Sheet: Soil moves off as a horizontal layer. Rill: Fast moving water cuts small channels Gully: Extreme case of Rill erosion

Desertification: The creation of “Desert-like” conditions due to over grazing, over cultivation, and excessive irrigation

Salinization: Water that’s not absorbed and evaporates leaving behind dissolved salts in the topsoil .

Dust Bowl 1930’s

Plowing the prairie resulted in loss of natural grasses that rooted the soil. Drought and winds blew most of the top soil away!!

Relevant Laws Soil Conservation / Erosion Act 1935. Established Soil Conservation Service. Protect the soil. Paid farmers not to grow crops in some areas. Soil and Water Conservation Act 1977. Requires USDA to periodically prepare a national plan for soil and water conservation