It was an earthquake. It sent a series of massive waves across the ancient sea that covered part of western Canada and the northern United States. The tsunami that devastated Canada occurred 445 million years ago. This is the conclusion of two researchers from the University of Saskatchewan (USask). They found evidence of a tsunami in a shallow inland sea. Their study is published in Sedimentary Geology.
Tropical sea in Canada
Saskatchewan and its neighboring areas are today very far from the sea. But in the period called Ordovician, the region had a very different appearance. Much of what is now Saskatchewan and Manitoba was covered by a sea known as the Williston Basin.
«It was a completely different environment. We were much closer to the equator than we are today and the sea level was high. “It was just a tropical inland sea,” co-author Colin Sproat said in a statement. He is an assistant professor in the Department of Geological Sciences at USask.
Pratt and Sproat visited three sites north of The Pas, Manitoba. There was evidence of a brief, high-energy event in this ancient sea. It had gone unnoticed by geologists until now. Certain sediment beds at the sites had been cut into pebbles and mixed with clay. The soil beneath the deepest waters of the basin contained no clay. It could only come from the earth.
“It had to be an event that ripped up the sea floor and then came back with all this clay,” they said.
3D perspective
The answer could only be a tsunami. There was no animal life nor almost any plant life on earth to witness that day almost 500 million years ago. But if an observer had been nearby, he would have seen a dramatic event.
In the last decade, several new quarries have been excavated in northern Manitoba. They revealed more secrets of the basin. «It was checking the quarries that opened our eyes. We enter these quarries and we can see the layers. They extend laterally for 100 meters or more. It gives us an unusual 3D perspective. The tsunami that devastated Canada left traces that remained hidden. When revealed, they show an environment unlike any other place on the planet today.
