Gea Norvegica

Skien municipality's bedrock consists of a multitude of rocks with different ages and different stories.

Oldest is the old bedrock that makes up large parts of the municipal area to the west. The rocks found here are over 1 billion years old, and are therefore called pre-Cambrian rocks. Most commonly used are granite, gneiss and amphibolite.

In Skien you can visit Kapitelberget where you can see the ruins of a crypt church, there are only 4 such church ruins in Norway. Glasergruva is the first mining plant of Fossum Jernverk, and the first iron mine that can be timed in Norway, built in 1543. It was operation at Fossum Jernverk until 1876. Today, Glasergruva is a protected cultural monument.