A trio of Earth and atmospheric scientists at the University of Houston, working with a geoscientist from the University of Arizona, has found evidence that a geographic hotspot laid the groundwork for the formation of the Great Lakes.
In their study published in the journal Geophysical Research Letters, the group studied models depicting the movement of the Pangea supercontinent over millions of years and the site of the Cape Verde hotspot, which still exists today.
Prior research has shown that the Great Lakes were formed by ice movement during the last Ice Age—as the ice melted, it filled the lakes with water. In this new study, the researchers found evidence of a hotspot beneath the site of the Great Lakes that allowed more land to be scooped out, making the lakes deeper than they would have been otherwise.
The team began with research into the formation of the North American continent. They were looking at how seismic waves moved horizontally under the Great Lakes, rather than vertically, as they did in the ground around them. This finding suggested that the lithosphere had been deformed somehow, but the researchers did not know the cause.
It was only when they began working with a colleague from the University of Houston that things became clear. Geologists there had been creating models showing the movement of tectonic plates going back hundreds of millions of years. In looking at the models, the researchers found that the Cape Verde hotspot was once located directly below the current location of the Great Lakes.
Hotspots are cracks in the mantle—they allow hot material to leak upward into Earth’s middle layers, where they at times interact with the crust in the form of volcanoes. They can also appear to move slowly over very long periods of time.
The model showed the Cape Verde hotspot directly below Lake Superior approximately 225 to 300 million years ago. As the supercontinent Pangea shifted above it, the hotspot remained in place, but its position relative to the land above would make it look like it had moved, allowing the hotspot to reside over both Lake Huron and Lake Erie before “moving” farther east, eventually residing below the island of Cape Verde.
The research team also found that the odd seismic waves lined up with the continental pass over the hotspot, which would have left the ground beneath the hotspot more fragile, allowing the ice that passed over 20,000 years ago to scrape out more soil, making the lakes much bigger and deeper than they would have been otherwise.
More information:
Zhongmin Tao et al, Revealing the Cape Verde Hotspot Track Across the Great Lakes, Geophysical Research Letters (2024). DOI: 10.1029/2024GL110777
© 2025 Science X Network
Citation:
Scientists find evidence that ancient ‘hotspot’ played major role in formation of Great Lakes (2025, January 8)
retrieved 8 January 2025
from https://phys.org/news/2025-01-scientists-evidence-ancient-hotspot-played.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.