The large annular lake in this image represents the remnants of one
of the largest impact craters still preserved on the surface of the
Earth. Lake Manicouagan in northern Quebec, Canada, surrounds the
central uplift of the impact structure, which is about 70 kilometers in
diameter and is composed of impact-brecciated (relatively large pieces of rock embedded
in finer grained material) rock. Glaciation and other
erosional processes have reduced the extent of the crater, with the
original diameter estimated at about 100 kilometers (60 miles). This natural-color
image of the region was acquired by the Multi-angle Imaging Spectroradiometers
(MISRs) nadir (vertical-viewing) camera on June 1, 2001.
The impact that formed Manicouagan is thought to have occurred about
212 million years ago, toward the end of the Triassic period. Some
scientists believe that this impact may have been responsible for a mass
extinction associated with the loss of roughly 60 percent of all species. It
has been proposed that the impact was created by an asteroid with a
diameter of about 5 kilometers. The lake is bounded by erosion-resistant
metamorphic and igneous rocks, and shock metamorphic effects are
abundant in the target rocks of the crater floor. Today Lake Manicouagan
serves as a reservoir and is one of Quebecs most important regions for
Atlantic salmon fishing.
NASA image courtesy NASA/GSFC/LaRC/JPL, MISR Team.
The impact that formed the lake is thought to have occurred about 200 million years ago and may have caused a mass extinction event.
Lake Jänisjärvi is a roughly oval-shaped lake, some 13 by 17 kilometers (8 by 11 miles) across, in northwestern Russia, near the Finnish border. The basin for this lake was formed hundreds of millions of years ago by a meteorite impact.
Crater Lake is formed from the caldera of Mount Mazama. Part of the Cascades volcanic chain, Mount Mazama sits between the Three Sisters volcanoes to the north and Mount Shasta to the south. The catastrophic eruption of Mount Mazama that occurred approximately 7,700 years ago destroyed the volcano while simultaneously forming the basin for Crater Lake. Eruptive activity continued in the region for perhaps a few hundred years after the major eruption. Evidence of this activity lingers in volcanic rocks, lava flows, and domes beneath the lake surface; the small cone of Wizard Island is the only visible portion of these younger rocks. Although considered a dormant volcano, Crater Lake is part of the United States Geological Survey Cascades Volcano Observatory seismic monitoring network.
Some 400 million years ago, a meteor struck Earth in what is now Canada’s Northwest Territories. The 12.5-kilometer- (7.8-mile-) wide crater is now Nicholson Lake, one of many small lakes that dot the sub-arctic, glacier-scoured landscape.