Scientists think the Great Lakes formed over a region where an ancient hotspot once lurked. That hot spot has traveled for around 300 million years and is now in the Atlantic Ocean. (Image credit: Posnov via Getty Images)
LiveScience has an interesting story about the origins of the Great Lakes and why they formed in their specific location around 20,000 years ago. A new study published in Geophysical Research Letters suggests that the Cape Verde hotspot, which still exists beneath the island nation in the Central Atlantic Ocean, played a key role in shaping the region. A geologist from the University of Houston, while reconstructing the movement of tectonic plates, discovered that the Cape Verde hotspot was once located beneath Lake Superior between 300 million and 225 million years ago. Over time, it drifted eastward, passing beneath west-central New York and central Maryland, before reaching northern Virginia and eventually moving out to sea around 170 million years ago. This heating and stretching of the crust may have influenced the conditions that later led to the formation of the Great Lakes.
Hotspots are plumes of hot material that rise from the mantle, Earth's middle layer. When hotspots interact with the crust, they can create volcanoes, such as the Hawaiian Islands. Yellowstone National Park also formed because of a hotspot, which left a trail of volcanism through Oregon, Idaho, Montana, Nevada and Wyoming as the North American continent crept over it.
The traces of ancient hotspots are harder to detect, as old volcanoes erode. However, there are two hotspots in the Atlantic today — the Great Meteor hotspot and the Cape Verde hotspot — that geologists know, based on how the tectonic plates have moved over hundreds of millions of years, must have once been under North America. The Great Meteor hotspot traced a line under what is now the border of Ontario and Quebec and then cut across modern-day Vermont and New Hampshire and out into the Atlantic between 150 million and 115 million years ago. This process is confirmed by the presence of kimberlites, rocks from rapid volcanic eruptions that can carry diamonds to the surface.
