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This interesting soil profile was formed by alluvial (water deposited) materials along the Paint Branch Creek, in College Park, Maryland.  Because the soil is within the flood plain of the creek, the colors of the horizons you see are the result of different materials that were deposited year after year by flooding. The floods have carried materials from up stream to this location and further, from as far away as the Eastern Shore of Maryland.

At first glance, you can see two horizons which are darker than the others. The one on top is the most recent, and its dark color results from the addition of organic matter from the trees and grasses that are growing at this site along the creek. The properties (structure, color, texture) of the soil horizons just below this surface layer indicate that they were formed from different flooding episodes which carried materials of varying physical and chemical composition.

The second dark layer is a layer of charcoal that was deposited approximately 250-300 years ago. This charcoal resulted from slash and burn agriculture that was going on in the Maryland area at that time.

The horizon directly below the layer of ash has a lot of oyster shells in it. This deposit occurred approximately 400-450 years ago. At that time, native Americans living in the Eastern Shore of Maryland ate lots of oysters. Scientists believe that the shells of those oysters traveled upstream to be deposited in this area.

(Thanks to Dr. Ray Weil of the Unviersity of Maryland for letting us use these photographs)

Landscape at Paint Branch Creek

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