Remmarna

Melting water brought sand and clay here

About 20,000 years ago the thick inland ice covered the land that today is Sweden. In due course the ice melted. Geologists are not entirely certain but Ragunda was probably free from ice some 10,000 years ago.

When the inland ice was melting the water gushed into the bay in the Baltic Sea at the time reaching into the valley of the River Indalsälven. At the time Sweden was pushed down by the heavy ice and the Baltic Sea had a different layout compared to the present.

The melting water carried along large quantities of sand and clay. The material was deposited on the bottom of the lake. One light, a little thicker layer was added every summer, and a dark, thinner layer was added every winter.

This process repeated every year until the point when no more material from the melting ice could reach here. At that point the land uplift had continued and the Baltic Sea retreated. What remained in the area was Lake Ragundasjön.

De Geer discovered the time when the ice age came to an end

Gerard De Geer was a famous professor of geology at Stockholm University. Early in the 1900s De Geer and his students came to Ragunda to count varves – layers – and attempt to determine the point in time when the latest ice age had come to an end. He knew that Lake Ragundasjön had been emptied of water which meant that the varves were easy to study.

The uppermost layer dated from 1796, the year when the lake was emptied and the bottom layer was approximately 7 000 years old. Since the varves are unique they were able to make comparisons with other, corresponding layers in other places, where they could count more layers back in time.

When De Geer had finished counting, his conclusion was that the end of the latest ice age should have happened about 12,000-13,000 years ago. Nowadays, geologists believe that Ragunda was ice-free about 10,000 years ago.