The land beneath the nation's capital could sink by more than 6 inches in the next century, according to a new study.

Geologists have long suspected that Washington, D.C. once sat atop a prehistoric ice sheet. That sheet, however, has long since melted, leaving the earth to settle slowly back to its original levels.

To confirm their hypothesis, University of Vermont researchers drilled more than 70 boreholes (up to 100 feet deep) into the land around the Chesapeake Bay, which is already rising twice as fast as other bodies of water around the world. They then analyzed sediment to determine historical land movement, ultimately determining that the mid-Atlantic region is now "early in a period of land subsidence that will last for millennia".

Interestingly, the sinking doesn't appear to have been exacerbated by human influence -- although the impacts of such sinking will almost certainly be intensified by rapidly rising sea levels.

"It's ironic that the nation's capital -- the place least responsive to the dangers of climate change -- is sitting in one of the worst spots it could be in terms of this land subsidence," said study senior author Paul Bierman. "Will the Congress just sit there with their feet getting ever wetter?"