The Rising Tide -
Cause, Effects and Planning
for Rising Sea Level

Once Upon a Time…

About, 35 million years ago, during the late Eocene epoch, a comet struck the Earth near the present Cape Charles, blasting out a crater and contributing to a major global extinction event. At that time, the ocean shoreline ran along today’s fall line from Washington, DC through Richmond, with I-95 roughly marking the beachfront. The effects of that impact are still being felt along the current shoreline, as we shall see shortly.

Fast forward to 14,000 years ago when the glaciers covered most of the northern range of North America, sea level was about 120 feet lower than today, and the Atlantic coastline was about 60 miles offshore, near the current continental shelf of the east coast. Virginia was on the southern end of the North American continental plate overlain to the north by the glaciers. Like a teeter-totter, the weight of the glaciers to the north raised Virginia slightly into the air.

Then, about 10,000 years ago, the glaciers began to melt and the oceans rose, with the Virginia coastline moving westward, at one point at a rate of over 3 feet every 20 years. In time sea level rise slowed, stabilizing near the current coastline about 3,000 years ago, although gradual sea level rise has continued very gradually since then

Evidence of this gradual rise is around us now. In the midst of the 400th Anniversary of the landing at Jamestown, it is relevant to note that Jamestown Island was not an island when John Smith arrived. In 1607, it was connected to the mainland by a land bridge that is now under about four feet of water. As the water has risen, and the land has subsided it has also inundated part of the original settlement at Jamestown.

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