Today, the desert country of Namibia isn't somewhere you'd expect to find much ice, but 300 million years ago it was home to a very different landscape. A team of geologists studying volcanic rocks in the southern African country has now discovered a land formation that's associated with fast-moving glaciers, and isn't usually found in the desert.
Drumlins are a distinct type of hill, where the ground rises fairly steeply at one side and then tapers off in a more gentle slope down the other end. They're usually found in groups where the "tails" all point in the same direction, producing a bumpy terrain that's easy to spot. Drumlins are known to be created by glaciers, and the direction of the tails indicates which way the ice was moving.
These formations are usually found in places you'd probably expect to have once been covered in glaciers – they're common in Canada and the northern states of the US, as well as England, Ireland, Scotland, Sweden, Germany, Finland and Greenland.
That makes the newly discovered drumlins in Namibia unusual. Graham Andrews and Sarah Brown, geologists from West Virginia University, were in the country on other studies when they recognized the characteristic shapes of the hills. They soon realized that the drumlins hadn't yet been described in the literature.
The researchers went on to use Google Earth and Google Maps to measure the height and length of the formations, finding that they ranged from 0.1 to 1.5 km (0.06 mi to 0.9 mi) long. They also found large grooves in the drumlins, indicating that the ice above them had to have been moving pretty fast to carve them out.
Taken together, those findings indicate that a fast-moving ice stream, flowing towards the northwest, had been present over the area some 300 million years ago. At that time, the land that is now Namibia was located somewhere over the South Pole. It also suggests that an ice stream could be responsible for similar formations seen in southern Brazil, which would have been connected to Namibia around that time.
The research was published in the journal PLOS One.
Source: West Virginia University
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