The Chesapeake Bay is a geological result of the last Ice Age. As the glacier that covered much of North American melted some fifteen thousand years ago, sea level rose, flooding the lower Susquehanna River basin and creating the Chesapeake Bay. With the exception of the portion that was originally the Susquehanna River channel, the Chesapeake Bay is relatively shallow. The old river bed itself is the current deep Bay channel. The bulk of the watershed was originally forested.
Trees play several roles in maintaining a healthy watershed.
They buffer heavy rainfall which otherwise pelts the earth, causing soil to wash away. Trees absorb and evaporate large amounts of water during the growing season, thus reducing flood potential. As people moved into the watershed and cleared trees from the land, there has been a substantial increase in soil erosion, flooding and the delivery of sediment, nutrients, and other materials into the major tributaries of the Bay. Life in the Chesapeake Most of the living things in the Chesapeake Bay are much too small to see with the naked eye. Microscopic plants and animals, known as plankton , are perhaps the most important species in the Bay.