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A newly discovered field of mounds and hills aren’t where anyone thought they should be. Called drumlins, they form when glaciers move over the land at a very fast pace. They create the telltale hills and divots that gave away what these were – it only took 300 million years to figure it out even though the drumlins were in plain sight the entire time.
Millions of people, including researchers, knew they were there in the desert of Southern Africa. Namibia to be exact. The geologists who found them, Graham Andrews and Sarah Brown, were studying volcanic rocks in the area when they stumbled on the formations.
“We quickly realized what we were looking at because we both grew up in areas of the world that had been under glaciers, me in Northern Ireland and Sarah in Northern Illinois … It’s not like anything we see in West Virginia, where we’re used to flat areas and then gorges and steep-sided valleys down into hollows.”
They realized these were drumlins because of the way they know glaciers form, sit, move, and melt. Most glaciers grow and melt, but don’t move much, so the land they sit over is smoother than what they found, which had divots and large grooves. These could only have been carved out by glaciers that were moving very rapidly over the land.
The evidence shows that it happened about 300 million years ago, during the late Paleozoic Age, which is an astounding find. Although drumlins have been found over the years, indicating rapidly flowing ice streams and fast-moving glaciers, this is the first time that researchers found evidence of them in Africa.
This is because no one researched these particular formations before, apparently assuming they were your run of the mill hills or dunes. By definition, drumlins are typically teardrop shaped. And the direction they sit indicates the direction the glaciers were moving when they formed them, with the elongated side showing that direction.
That these are drumlins formed by rapidly moving ice streams and glaciers in Southern Africa opens up a whole slew of thinking, and questions that need answers.
For starters, the impact on what we know about how and when the Americas and Africa broke up into separate continents in huge. At one point in our geological history, all of our continents are pieces of what was once one supercontinent called Gondwanaland, which existed about 200 million years ago. South America and Africa were joined during this time.
Before this came Pangea, which was a supercontinent that consisted of nearly all landmasses on Earth. That’s the landmass that contained North America as well, and it broke up starting around 300 million years ago, which is the time these drumlins in Africa come from. The researchers say that the presence of the formations is more evidence that the continents were indeed joined.
The drumlins are also a huge impact on what we know about our past climate and how it changed, as well as how it can help researchers learn more about how our past will impact our future climate, including how we study it. For instance, finding evidence of an ice river and drumlins in Africa confirms that Africa was a part of the South Pole at the time the drumlins formed.
We could also use this new information to learn more about when the next continental shift will happen, or when the continents will combine and break up again. Something that we’re apparently overdue for a continental shift, as they combine and separate every 300 to 500 million years.
Read more about the original discovery in the researchers’ scientific paper on the topic here.
Featured Image via WVU/Public Domain