HIETAKANGAS ESKER IN ALAJÄRVI
There is an interesting esker landform in Hietakangas area, which runs for several kilometers on the southern and southeastern sides of Lappajärvi. They formed near the end of the ice age close to the edge of the glacier, where meltwaters running within the glacier deposited sand and gravel.
The Hietakangas esker was formed about 10 500 years ago. In Southern Ostrobothnia eskers tend to be quite shallow. This is because right after the ice age the region was under the sea for a long time. Clay and silt deposited on the seafloor are now covering eskers in many places.
Impactite sandpits
In Hietakangas you can find rock types related to the collision, such as impactite, suevite, impact breccia, as well as older sandstone that has sunk into the crater. In addition, one can find impactites altered by the hydrothermal phase of the crater’s evolution. The impactites remained hot for up to million years after the impact, creating a system where hot fluids circulated within the rock mass changed the composition of the slowly cooling rocks. Thus, rare minerals emerged.
Impact diamonds
Besides the suevite found in Hietakangas and in other areas southeast of the crater, scientist Marjatta Koivisto discovered first impact diamonds in Nordic countries in the late 1990s.
The diamonds are only up to 0.2 mm in diameter, formed from graphite flakes present in some mica schist and gneisses. The largest diamond is 0.4 mm and was found at a diamond exploration course held at Kivitippu hotel. Impact diamonds have no economic value or any industrial use, but scientifically they are significant.
Many of us are fascinated by stones and some even have their own collection.
Are you aware of everyone’s rights to possess stones? — Soil materials such as stones may not be taken from foreign land and water. A small amount of stones may be collected if there is no greater harm. Foreign land may not be excavated. Samples may be taken for geological research.
More information: Craterlake Geotrail, destination 9
Location: Google Maps
