The Great Lakes Zephyr - Wind Energy & Hydrogen Journal

United States sinking, Canada on the rise

By CHRIS LACKNER
Globe and Mail Update

The United States is slowly sinking, and Canada is on the rise – all thanks to a glacier that melted over 12,000 years ago.

Scientists have discovered that the melting of North American glacial sheets is still shifting the makeup of the land.

For one thing, the shift is causing Canada's Great Lakes to slip slowly southward. Chicago, for example, is sinking at a rate of 1 millimetre a year.

At current rates, Chicago's Sears Tower will be below water in approximately 462,686 years.

“For years we've studied the history of the glaciers retreat and how it created land mass,” said Seth Stein, a Northwestern geological science professor that helped organize the new study. “But new measuring techniques are allowing us to see [the details].”

Mr. Stein and his coworkers measured how global plate motions over time compared with those from over a few years. Their detailed measurements were uncovered using Global Positioning System satellites.

The team used 10 years of readings from the satellites from more than 20 North American locations in order to measure the shift.

“Space-based techniques allow us to measure positions on the earth far more precisely than anyone dreamed possible a few years ago,” he said. “We now have the data density needed to see these variations.”

Over 20,000 years ago the glacial sheets created depressions and other natural features in the North American landscape, including the Great Lakes. When the ice began to melt – a process that began 12,000 years ago – the land slowly began to...(Full Story)