Today, in the lovely spring weather we have here in the south of Sweden, I took a small trip out to the nature reserve called Billebjer just outside my town of Lund. It’s part of the horst that is called Rommeleaasen, a horst that is part of a greater geological system called Tornqvist zone. Basically the Tornqvist zone is a lot of ancient faults stretching from the Black Sea to somewhere outside Scotland. This zone begun to form some 300 million years ago and the horsts was raised some 60 million years ago.

Most of the rocks are difficult to identify by visual means since the bedrock is covered with growth and heavily cracked and eroded. And fresh surfaces of bedrock only reveal a diffuse rusty rock. But looking at the bedrock up close revealed more typical traits of a granite. And small traces of a metamorphic process could also be seen. But I was far from sure so I had to cheat and look it up at the webpage of the Swedish geological survey. According to them it’s a Orthogneiss. But Im not completely convinced and some pages on the internet talk about a granite-gneiss. That is, a only slightly metamorfed granite. But other sources talked about an Amphibolite rock that also is common in this horst. Well, my guess is a very iron rich granite-gneiss perhaps. Its so full of this "rust" that its almost impossible to see what it is. It almost looks like a sedimentary rock at a distance. But that much I know, it isnt.

Igneous bedrocks are not the dominate bedrock in the very south of Sweden (where I live). Most of the bedrock here is sedimentary and the metamorfed or igneous rocks are hidden deep below or only revealed through horsts. The Billebjer formation is one of few spots where I can look at the bedrock in close vicinity of Lund. North of the Tornqvist zone the igneous bedrock becomes more and more common. And basically 90% av the Swedish topside bedrock is metamorfic or igneous. The province of Scania (Skåne) where I live and the island of Gotland are the exceptions and especially here in Scania you can find all sorts of bedrock. From 2 billion year old igneous rocks to tetriary sedimentary deposits.