Gotland is an island, which brings into sharp focus the tremendous forces of time and Mother Nature. It's made me realise how geography is not static but ever moving. A lesson which those who live in such stable earth as Scandinavia easily forgets.
It’s generally said that one should know two things to understand the creating of Gotland: the era called Silur and the latest ice age.
Unlike most islands of this size it was not fragmented from a larger land mass or volcanoes but was created in the sea from fossils. In the old days the scientist had problems understanding that because Gotland was made of fossils from animals and plants that can't live in such cold water as the Baltic Sea. In the beginning of the 18 century the German Alfred Wegener had his thoughts about what happened, but it was not before 1960 that the theory about continents and the sockets they floated around on, gave credence to Wegeners ideas.
During the very long period of time called Silur, starting 400 million years ago, Gotland was situated near the equator, and that means in a warm and not to deep sea. There weren't any animals such as dinosaurs on the land, but there were plenty of fish and plants in the sea. Great amounts of sand, mud and limestone gathered on the bottom of that sea and hardened to a solid land mass. After that different kinds of lime and sandstone formed atop this landmass creating the island which then became covered by younger limestone which can be easily seen today.
When these rock where made, enormous amounts of simpler forms of animals in the sea existed. When they died the harder parts of them, shells and skeletons, were covered by the mud in the warm sea and became petrified to fossils of which one can easily find a lot of today. About 1,500 different kinds of fossilized animals are known today which have been found petrified here such as early fishes, scorpions and plants (but only limestone alger).
Lime stone formations
A limestone formation is called a "raukar" on Gotland. They mostly are made of sea lilies which are the hardest parts of the reefs created by Silur and not pushed away by the latest ice period.
The ice age
From the times after Silur there’s no traces left after rock creation. First during the Kvartar period, which are close to our age, there’s been found some rock. They where found during the last ice age (starting about 70,000 years ago, the ice started to melt 55,000 years later) when all of northern Europe was covered by a couple of hundred meters of ice. Under the mass of ice were created leftovers, some we call pinnlera, which today cover a large part of Gotland and therefore is a common type of ground and accounts for the unusual variety of flowers found here. The big mass of ice inched slowly backwards as skrid-jöklar (the glaciers in Iceland) do today bringing with them large and small stones which here and there are deposited on the ground leaving deep rifels.
Most big rocks were blown to pieces a couple of hundreds years ago, but Bastustain in Rone and Silvastain in Lojsta are two big blocks still remaining fully intact. When the ice made it's final retreat 15,000 years ago, the Baltic sea was a lake called the Baltic lake which held sweet water and free floating ice bergs.
/text Daniel Behr, foto Björn Pettersson