Rognstranda

Here at Rognstranda, you'll find to different geological worlds, and can walk across 1,5 billion years of geological history in just a few minutes.

From the old gneiss rocks, that shape the skerries, to the youngest history we can observe in the limestone cliffs, the characteristic ''flauene'' that is typical for the Grenland area. The Gneiss here is approximately 1.5 billion years old, and belong to the time period Precambrium. The slate and limestones on the other side of the bay is ''only'' 500 million years old and belong to the geological time periods Cambrium, Ordovicium and Silur. Gneiss is formed deep down in a mountain range, while the limestone was formed in a shallow ocean. Therefore these rocks represent two different worlds on each side of the bay.

The Oldest and Youngest Geology in Gea Norvegica Geopark

After the mountain range had eroded, approximately 500 million years ago, all of Southern Norway consisted of relatively flat plains. Over these plains, the ocean flowed in. In this age, Norway was South of the Equator, and in the ocean a diverse animal life thrived. Most of these organisms had a calcium shell, and when they died, these shells deposited layer after layer on the sea bed. Together with sand and clay, the calcium formed the slate and limestone you can see in the cliffs here.

This type of landscape with steep cliffs of slate and limestone is typical for the Grenland area, and is a result of 250 million years of erosion. Locally, these cliffs are called 'flauer'.

The Gneiss in the foreground of Rognstranda has a vertical structure, while the limestone and slate has a horizontal structure. A divide like this is called a discordans, and in Rognstrande the age difference between the two layers is approximately 500 million years. These types of divides is proof of a fundamentally important geological event having occured.