Image: Clearwater Lakes 2013180 labels

Description: About 290 million years ago, two large asteroids smashed into Earth. The massive craters they left behind—now lakes—are still visible from space. Astronauts have noticed and photographed the craters for decades, and the Operational Land Imager on Landsat 8 captured a new image of Clearwater Lakes (Lac à l‘Eau Claire) on June 29, 2013. The small inset box toward the lower left marks the area shown in the lower image. When they struck, the binary asteroids crashed into a part of Earth’s crust that was fairly close to the equator. Since then, millions of years of plate tectonics have pushed the craters north into what is now northwestern Quebec. A mere 20,000 years ago (not long from a geologic perspective), massive sheets of ice covered northwestern Quebec, much like ice now covers Antarctica and Greenland. During that period, ice sheets repeatedly advanced and retreated, scouring the land of soil and rock during cool periods, and then carving deep channels and rinsing the landscape with melt water during warmer periods.
Title: Clearwater Lakes 2013180 labels
Credit: http://earthobservatory.nasa.gov/IOTD/view.php?id=82433
Author: NASA Earth Observatory images by Jesse Allen and Robert Simmon, using Landsat 8 data
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