What geographical feature is described below: A piece of very fertile flatland made of silt left behind as a river drains into a larger body of...

Deltas are wetlands that form as rivers deposit into larger bodies of water like oceans or seas.  Examples of deltas include the Mississippi River Delta and the Nile River Delta.  The Mississippi River deposits into the Gulf of Mexico while the Nile River travels to the Mediterranean Sea.  Deltas form a triangular shape as they enter the larger body of water.  This is because the river naturally slows down, and silt is built up in that area.  Generally, the river will branch out into several tributaries that deposit into the ocean or sea.  The richest of the soil is the sediment that remains under the water of a delta, usually at the mouth of the river.  Because of the richness of the soil, deltas are important geographical features.