See How Ice Can Scar The Ocean Floor Enough To Be Seen From Space

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Lying on the cusp of the vast steppe of Central Asia and the soaring Caucasus Mountains, the aquamarine salt water of the Caspian Sea has a unique beauty.But images captured by Nasa’s Landsat 8 satellite has revealed something strange is scarring the world’s largest inland sea.

image credit: Science Channel 

Mysterious lines have been spotted crisscrossing in the shallow waters of the North Caspian close to the Tyuleniy Archipelago, in Kazakhstan.Thousands of the unusual marks can be seen clustered close to the coastline in the images.It’s possible that some of the marks have a human origin. Similar lines show up in the world’s oceans because of trawling.

image credit: Science Channel 

But the scientific literature and a January satellite image suggest that a majority of the marks in the images were gouged by ice. In January, blocks of ice stand at the leading end of many lines, most notably in the northeast corner of the image. By April, ice has melted and only the scour marks persist.

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Stanislav Ogorodov, a scientist at Lomonosov Moscow State University who has published research on the phenomenon, agrees: “Undoubtedly, most of these tracks are the result of ice gouging.” Ogorodov notes that this part of the Caspian is very shallow—about 3 meters deep. Ice that forms here in wintertime is usually about 0.5 meters thick, so most of it never touches the seafloor.

But the ice tends to be “warm” and thin, which gives rise to relatively weak ice cover that is easily deformed by wind and currents. When pieces of ice are pushed together, some ice is forced upward and downward into so-called “hummocks.” The keels of hummocks, frozen into the ice fields, can reach the seafloor and scour the bed as the ice moves.

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