Sten – Stockholm

I am a block of bright red granite from Väddö in the Roslagen archipelago, so I am from Stockholm County. As you can see, I'm quite rounded, so I've probably been transported a bit by the latest inland ice. In that case, it is not certain that I really come from the bedrock on Väddö, perhaps I come from further north, perhaps from the bottom of the Åland Sea.

The bedrock on Väddö is otherwise quite varied if you look at a geological map, but most of it consists of gneissic granites that have an age between 1910 and 1870 million years. On the geological map (SGU's Map Viewer) these are marked by a brown color.SGUs KartvisareBut since I am light-coloured and look completely massive, i.e. I have no visible gneissic structure but the mineral grains are scattered without any defined orientation, it is more likely that I belong to the younger granites that have ages between 1830 and 1750 million years. The Stockholm granite in Täby and Vallentuna, for example, is about 1790 million years old. So we assign an age of about 1800 million years to the granite block from Väddö, with a question mark after, because you can't be absolutely sure. There are some small areas with such younger granite (pink-coloured on the map) on the geological map also on Väddö.

Geologist Åke Johansson
Swedish Museum of Natural History