Sten – Kronoberg

I am a block of red Växjö granite, a type of Småland granite, from Urshult south of lake Åsnen in southern Småland, in Kronoberg county. Since I am a loose block that was transported with the inland ice, I hardly come from the bedrock right at Urshult, which is of volcanic origin, but a little further north, where the bedrock is dominated by Växjö granite. The red Växjö granite, which is approximately 1770 million years old, is a medium-coarse variant of the Småland granites. It is also Småland's landscape stone.

At that time, Sweden and all of Baltica, i.e. the north-eastern part of today's Europe, were becoming part of the supercontinent Columbia which was being formed. All, or almost all, of the Earth's continents were gathered into this supercontinent, although it is not known exactly what it looked like and where all the continents of the time were located. But Sweden was quite certainly close to the edge of this supercontinent, facing the ocean, and along this margin there was a lot of activity. Between about 1810 and 1750 million years ago, magmas intruded to form granites and related rocks in a north-south belt that stretched from Blekinge and Småland in the south, up through parts of Östergötland to Värmland, and then into what is now the mountain range (it didn't exist then) all the way up to Lofoten in northern Norway. So I am one of all these granites. Some of the magmas, especially in Småland, flowed out onto the land surface of the time and formed volcanic porphyries, much like the Dala porphyries a hundred million years later.

So in Småland, where I come from, these granites and porphyries are called Småland granites and Småland porphyries, respectively. And Växjö granite is a variety of Småland granite.

In contrast to the gneisses further west, in western Småland and Halland, the rocks in the granite-porphyry belt through eastern Småland are quite well preserved, even though we are about a hundred million years older than the gneisses. But we have been more sheltered and not affected by any major mountainbuilding event with deformation and metamorphism (transformation at high pressure and high temperature) since we were formed. That is why we have retained our youthful appearance, despite our age. In Blekinge, the rocks are also more deformed than in eastern Småland, although they are of roughly the same age as the Småland granites.

Geologist Åke Johansson
Swedish Museum of Natural History