How was the Chesapeake Bay Created?
The Chesapeake Bay is a geological result of the last Ice Age. As the glacier that covered much of North American and northern Europe melted some eighteen thousand years ago, sea level rose, eventually 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. Sediment is accumulating more rapidly in the deep channel than in most other parts of the Bay, but its presence is a reminder of the history of the Bay’s formation.
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.