Mong & other dykes

58°22’47.57”N 6°06’53.42E

Mong & other dykes

Basaltic dykes in Eigersund

How to get there

Parking: Information board on FV44 towards Sokndal. Access Mong following signs from FV44. Parking by the road or at the end of the road. You can also park at the molo at Lædre and follow a walking trail to Mong (part of Dalane Kyststi).

Accessibility: Easy when accessing from FV44. Medium hard when hiking from Lædre.

Duration: Different options.

Special conditions:

  • Park at the parking place and show respect for private land.
  • Show respect to animals along the trail.
  • Don’t forget to close grinds behind you so that animals would not get away.
  • Dogs have to be on leash
  • Leave nothing but footprints!
What Three Words

Geology and nature

Mong and basaltic dykes

The youngest rocks in Magma Geopark is a set of basaltic dykes – called the Eigersund basaltic dyke swarm.

What is a dyke?

A dyke is a sheet of rock that was once molten and has crystallized (solidified) in a fracture of an already existing rock. The rock in a dyke is usually different from the already existing rock. The aspect ratio of a dyke is high, meaning that the thickness is small compared to the length and width. Thickness can vary from a few centimetres to several meters and the lateral extent can be many kilometres, which is the case for the dykes in Magma Geopark.

What is basalt?

Basalt is the most common type of volcanic rock on the planet. It can occur on the surface of the earth (basalt), in dykes (diabas/dolerite) and as large masses below the surface of the earth (gabbro).

How and when were these dykes formed?

About 900 million years ago all landmasses on Earth was gathered in one large supercontinent, called Rodinia.  About 750 million years ago the continent started to drift apart – continents separated and new oceans opened up. This was a slow process and it wasn’t until 650 million years ago that the continent Norway was part of started to drift of. The continent was called Baltica (Scandinavia + Russia + Ukraine) and it started to drift apart from the continents Laurentia (North America + Greenland + Scotland) and Amazonia creating the ocean Iapetus (the predecessor of the Atlantic Ocean) between them. As the continents started to split volcanic activity caused dykes to intrude into the bedrock here in Magma Geopark. Dating the rocks in the dykes gives and age of 616.3 million years – that is 300 million years younger than the surrounding rock anorthosite.

Where do we find dykes in Magma Geopark?

In total, there is 11 parallel dykes trending ESE-WNW. They can be found several places some being Mong, Tengs, Gaudland, Koldal, og Tellenes.

Pictures from Mong & other dykes

Download our brochure of locations

All locations in Magma Geopark: