Ælva

The watercourse that runs from Skien and flows into the Frierfjord was once part of an important transport route in earlier times.

The river marks the beginning of the Telemark Canal, which is now one of the county’s largest tourist attractions. Along the river and at its mouth, industries such as Union Fabrikker and Norrøna Fabrikker grew up, both examples of how location depended on access to raw materials. When standing on the Porsgrunn Bridge and looking upriver, you can see that the river makes a sharp bend.

From Skien and downstream, the river follows tilted limestone layers from the Cambro-Silurian period, as can be seen on a geological map of the area. But then the river suddenly bends and turns westward. The reason is that the river flows into a large fault zone that stretches from Porsgrunn all the way to Kristiansand. When the supercontinent Pangea began to break up during the Permian period, this was one of the places where earthquake activity and related movement occurred. If you look at a satellite image or Google Earth, you can see small and large lakes lying along the fault line far down toward Kristiansand.