Kånkback is a geologically and palaeontologically interesting site in Ragunda municipality where, in 1975, a well-preserved mammoth tusk was found in a gravel pit. Using the carbon-14 method, it was dated to approximately 40,000 years ago. At that time, the area was still under the influence of the Ice Age and was covered by a tundra-like landscape with grass, bushes and herbs, food that mammoths needed in large quantities every day.
Geologically, Kånkback consists of several distinct soil layers: at the bottom is a gravel pit with coarse material (stone, gravel, sand) deposited by a river during a milder climate about 40,000 years ago. On top of this is a layer of moraine: material transported and deposited by the inland ice sheet during a later glaciation. At the top is a thin layer of silt, which was probably deposited as bottom material when meltwater flowed into a fjord-shaped bay after the inland ice sheet pressed down on the landscape.
In addition, concretions (hard lumps of minerals) can be observed in the silt at the site, known as marleka. The word marleka comes from the words “mara”, nightmare, and "leksak”, toy. In ancient times, it was believed that people could avoid nightmares by having a marleka in their bedroom, as the mara, the nightmare, would then be busy playing with the stone.