New landform discovered from the depths of Finnish forest

Researchers Joni Mäkinen and Kari Kajuutti from the Department of Geography and Geology at the University of Turku studied Finnish landforms created by the last ice age with elevation models provided by the latest laser technology when they noticed peculiar, triangular-shaped landforms.

"First, we thought the landforms were an error in the laser scanning models, but when we found more of them and they formed sensible patterns, it began to dawn on us that we had discovered completely new landforms with the technology," says Project Researcher Kari Kajuutti.

Behind the new significant geomorphological discovery is Finnish national airborne laser scanning data. When it was found how to remove trees from the laser data, it became possible to create more detailed elevation models of the terrain.

"Despite this, it is puzzling that the landforms have not been discovered before. When we first set out to the field to look for these triangles, we weren't quite sure what to expect," says University Lecturer Joni Mäkinen.

The researchers' observations on the field helped them to understand why it was so difficult to notice the formations.

"The hillocks are mostly low and wide. Their height is from two to five metres and length is between one and two hundred metres. As the formations are covered by forest and nearly always located in remote areas, it would be quite a coincidence to come across them by accident and notice their triangular shape," explains Kajuutti.

Similar Landforms Discovered in Sweden

When the researchers realised that no one had discovered similar landforms before, they needed to give them a name. It turned out to be quite hard to come up with one. After some consideration, the researchers decided to call them murtoo. The name refers to the place where the formations were first discovered, Murtoo, which is located in the Pirkanmaa region, 30 kilometres from the city of Tampere.

"Murtoo is also a good name because it is derived from the Finnish word "murtomaa," meaning broken land, and the terrain in the area where the landforms were discovered is indeed broken -- it is filled with rocks and large boulders," describes Kajuutti.

The National Land Survey of Finland and the Geological Survey of Finland (GTK) have invested in mapping the Finnish terrain with laser scanning and the digital elevation models are openly available on the GTK website.

When observing these laser scanning models, the researchers discovered the triangles whose occurrence and formation they have studied ever since. They have also initiated collaboration with Swedish researchers, who have found similar formations in Sweden.

"Of course murtoos occur in Sweden as well. They had the same ice age as we had here in Finland. New discoveries will probably be made everywhere where glacial ice sheets have retreated. When climate gets warmer, the ice sheet melts and creates vast amounts of water. In suitable conditions, the melt water flowing under the ice shapes the deposits into murtoos."

The first scientific article on the landforms was published in Quaternary Science Reviews in the spring of 2017 in collaboration with the researchers of the Geological Survey of Finland. On the second week of January, the researchers presented their discovery and revealed the murtoo name at the Nordic Geological Winter Meeting in Copenhagen.