When was chesapeake bay formed

Some changes are sudden, whereas others take place over such a long period of time that we can only see them by looking back into geologic history. All geologic changes affect the Bay ecosystem, for better or worse. About 35 million years ago, a rare bolide—a comet- or asteroid-like object from space—hit the area that is now the lower tip of the Delmarva Peninsula, near Cape Charles, Virginia. This bolide did not create the Chesapeake Bay, but it helped determine that a bay would eventually be located there.

During the last Ice Age, mile-thick glaciers stretched as far south as Pennsylvania, and the Atlantic coastline was about miles farther east than it is today. Approximately 18, years ago, the glaciers began to melt, carving streams and rivers that flowed toward the coast.

Sea level continued to rise , eventually submerging the area now known as the Susquehanna River Valley. This drowned river valley became the Chesapeake Bay. The Chesapeake Bay assumed its present shape about 3, years ago. Remnants of the ancient Susquehanna River still exist today as a few troughs that form a deep channel along much of the bottom of the Bay.

To fully define the Chesapeake Bay ecosystem, we must go far beyond its shores. Although the Bay itself lies entirely within the Atlantic Coastal Plain, its watershed includes parts of the Piedmont Plateau and Appalachian Province. The waters that flow into the Bay have different chemical identities depending on the geology of where they originate.

The Atlantic Coastal Plain is a flat, lowland area with a maximum elevation of about feet. It is supported by a bed of crystalline rock covered with southeasterly dipping wedge-shaped layers of sand, clay and gravel. Water passing through this loosely compacted mixture dissolves many of the minerals. This led to the eventual submersion of what we know now as the Susquehanna River Valley.

In fact, the Bay is constantly changing due to the forces of erosion and sediment transport. For more information about the history of the Chesapeake Bay, visit our Bay History page. Do you have a question about the Chesapeake Bay? Please send it to us through our web comment form. Your question might be chosen for our next BayBlog Question of the Week! What forces of nature caused the Chesapeake Bay to form? This week's question comes from Samantha. Do you have a few hours to spare?

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