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Secret lake sets depth record

Natasha Kumar By Natasha Kumar Dec6,2023

Un secret lake establishes a depth record

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Image showing the former mouth of the Racine-du-Bouleau river , north of the former Manicouagan lake, which is now submerged. The former shore of the lake is indicated by the dotted line.

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At 320 meters deep, Lake Manicouagan is the deepest of Quebec's lakes, a new study from Laval University has discovered. But the lake is very humble. Despite this recognition, he hides far from the gaze of curious people, under the Manicouagan reservoir.

The work that led to this discovery began in 2014, under the direction of Department of Geography professor Patrick Lajeunesse. Already, at the time, Lake Manicouagan was only a memory in the memories of those who witnessed, in the 1960s, the creation of the Manicouagan reservoir, following the erection of the Daniel-Johnson dam .

The flooding of the outline of the crater, formed by the fall of a meteorite 214 million years ago, preserves under some 140 meters of water the landscapes of yesteryear. We still see rooted bushes and trees, as if life had stopped, says Professor Lajeunesse.

There we also find, towards the east, the banks of an arc-shaped lake, of unsuspected depth. Strangely, we had no idea of ​​the scale of this basin, admits Mr. Lajeunesse.

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Before being swallowed up by a hydroelectric complex reservoir, two lakes surrounded the Manicouagan crater. To the west, Lake Mouchalagan, and to the east, Lake Manicouagan.

In fact, no one knew the real depth of Lake Manicouagan until this day, but certain clues suggested that it was significant. We heard that fishermen were losing the signal from their sonar at the height of the lake, says the professor.

He and his team therefore appealed a cutting-edge tool, a multibeam echo sounder, to finally establish the true depth of Lake Manicouagan, 40 meters deeper than the previous record for a Quebec lake, that of Lake Walker, also on the North Shore.

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Three hundred and twenty meters deep, in addition to the 140 meters of the Manicouagan basin under which it is submerged: the deepest points of Lake Manicouagan are almost half a kilometer away.

< p class="StyledBodyHtmlParagraph-sc-48221190-4 hnvfyV">In addition to setting a record, this distance from the surface is of real scientific interest, since it isolates its background from bad weather, and even ice ages. Result: some 280 meters of accumulated sediment, mud, sand, gravel.

We call it sedimentary archives.

A quote from Patrick Lajeunesse, professor in the Department of Geology at Laval University

The hypothesis we have is that glaciers do not may not have had the opportunity to scrape the bottom of the lake, explains Mr. Lajeunesse. Thus, the bottom of Lake Manicouagan could reveal the key to soils, vegetation and ecosystems tens of thousands of years old.

As for the explanation behind the surprising depth of Lake Manicouagan itself remains a mystery. The shock wave from the meteorite could be to blame, but other factors too, suspects Professor Patrick Lajeunesse. We have no idea, he agrees. That's why we want to go back there.

  • Renaud Chicoine-McKenzie (View profile)Renaud Chicoine-McKenzieFollow
Natasha Kumar

By Natasha Kumar

Natasha Kumar has been a reporter on the news desk since 2018. Before that she wrote about young adolescence and family dynamics for Styles and was the legal affairs correspondent for the Metro desk. Before joining The Times Hub, Natasha Kumar worked as a staff writer at the Village Voice and a freelancer for Newsday, The Wall Street Journal, GQ and Mirabella. To get in touch, contact me through my 1-800-268-7116

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