Soil Deposits

1. Soil Deposits Soil Science Introduction to Agriculture

2. Remember: All soils come from matter known as _________ ____________. This material can be either organic or inorganic, and most soils are a combination of the two.

3. Role of Glaciers • Thousands of years ago, glaciers extended across the northern portions of America, Europe, and Asia. • Ice masses slowly moved southward, carrying along rocks that were in their paths • Till

4. Role of Glaciers • With the change in seasons, part of the ice would melt and freeze again • During especially mild periods, the front of the ice mass would melt and drop all debris (till) it had accumulated • Moraine

5. Role of Glaciers • The type of soil deposited is dependent upon the types of rocks that the glacier picks up • Moraines vary in the type and texture of the soil….some contain a lot of sand and some contain silt

6. Water-Deposited Soil • Moving water wears away rock and forms soil particles • Water is a major way that soil is moved from one place and deposited in another place • Alluvial soil • As long as the water is moving rapidly, the soil particles remain suspended • When the stream levels out and the water slows, the soil particles go down to the bottom

7. Water-Deposited Soil • Flood Plains

8. Water-Deposited Soil • Deltas • Ancient Nile would flood, leave fresh deposits of soil • Egyptian farmer developed calendars to predict flooding, and timed planting, cultivation, and harvesting to coincide with the flood • In the US, the Mississippi River has carried and deposited soil south for 1000s of year (Mississippi Delta) • Soils from the Midwest Delta are less productive because of erosion

9. Soil Deposits in a Lake • Lacustrine Deposits • Areas with large areas of lacustrine soils are areas around the great lakes, parts of ND, MN, NV, and the Pacific NW

10. Oceans • Marine Sediments • Areas include coastal areas of the Gulf of Mexico, parts of California, parts of the Great Plains

11. Soil Deposited by Wind • Wind creates and transports soil • Aeolian soils • Large particles are called sand and the deposits called sand dunes • In Saudi Arabia, vast areas are covered in dunes and continually move and change shape • Sand dunes are found in the western areas of the US • Little vegetation grows on dunes

12. Soil Deposited by Wind • Loess Soils • Found through Mississippi Valley, parts of the Midwest, Washington, and Idaho • Much of these soils are formed when the glaciers melted and climatic conditions turned dry (when the soil dried out, fine particles were blown by the wind to accumulate in new areas)

13. Soil Deposited by Volcanos • Many mountainous regions of the world have soil that was (and still is) being formed by the action of volcanos • Bring deposits of the soil from deep within the earth…some deposits are made when the volcano erupts and spews the deposits into the air

14. Soil Deposited by Volcanos • The lava turns to rock as it cools • The finest of the particles is volcanic ash • Usually the soil from volcanic ash is very productive • Found in Hawaii, Oregon, and Washington