Scientists may be learning a bit more about what lies beneath the ground with the help of one unusual tool: lasers. Scientists are using satellite laser imagery to better understand the drumlin hill.
Drumlin hills are shaped like an upturned boat. And while researchers have long known that they exist clustered together in distinct fields called swarms, they are unsure exactly how they formed. Scientists know that they were created at some point during the last ice age, but aren't exactly certain what type of action caused them to first appear.
Drumlin hills were first studied more than 150 years ago. At that time, researchers weren't sure whether the hills were built up over time or were created out of older sediment. In this case, the researchers decided to take a closer look at these features with the help of satellite laser imagery.
"Drumlin hills are the most studied and yet the most enigmatic ice age landform," said Nick Eyles of University of Toronto Scarborough. "Thanks to high resolution satellite imagery and new technology like LiDAR, we're literally seeing the surface of the planet for the first time and finding major surprises in the process."
So how do these hills form? They may actually be islands - sort of. It turns out that drumlins are a type of island of sediment. This sediment is actually in the form of a ridge. However, these are often bisected. In fact, drumlins are related to megaridges, which are part of a family of landforms that are created with the help of erosion.
What's interesting is that these hills are likely what was located beneath massive sheets of ice during the last ice age.
"They're essentially arteries moving huge volumes of ice toward the margin of the ice sheet," Eyles said. "the thinning and retreating of modern ice streams in a warming world has exposed their underlying beds which are seen to be megaridged, and that appears to allow the ice to flow faster across its bed by creating a slippery low-friction surface." He went on to say that, "The transition from drumlins to megaridges may record the final gasp of the ice sheet as it warmed up and began to stream over its bed."
The new findings reveal a bit more about drumlins. More specifically, they show how useful the new imaging technique is to learn a bit more about the geology of our planet Earth.
The findings are published in the March 2016 journal Sedimentology Geology.
