Kullstabergets utsiktsplats

Views of an undulating hilly landscape

Here you can enjoy the spectacular views of the undulating hilly landscape of mid-Sweden. The hills were formed some hundred million years ago at the time when Sweden was a desert and dinosaurs may have been grazing the Ragunda valley. The hot temperature meant that cracks in the rock weathered and were scooped out.

Cracks in the bedrock were scooped out to become valleys

Some 240 million years ago the landmasses had moved around so that Sweden was located in the approximate area of southern France of the present. The climate was extremely hot and our country was a desert. These conditions enabled crevices to crumble away, affecting the flat rock surface, the peneplain.

The weathering scooped out the cracks and formed valleys. The more hard-wearing sections of the bedrock were preserved as rounded or steep hills. Thus arose the undulating hilly landscape.

*Outlook over the undulating hilly landscape of mid-Sweden.* Photo: Souleiko Abdi Olade.

Peneplain – a flat stretch of rock

In these days the peneplain in the geopark consists of the high hilltops but in other places the peneplain may appear different. This is because the rock surface has been exposed to different activities.

In the crust of the earth there are areas or larger blocks of rock capable of moving upwards or downwards, straight or angled, towards or away from each other, because of movements in the innermost of the earth. A block pushed upwards will be exposed to faster and more aggressive erosion compared to a block that is pushed downwards and protected by loose deposits in the sea, for example.

The peneplain that can be seen in the province Västergötland, where the Platåbergen mountains ‘rest’ on the peneplain, was for a long period protected against erosion by a sea. The erosion-resilient rock diabase covered the tops of the hills and protected the more exposed species of rocks from erosion, leaving remnants called inselberg. In Ragunda there was no such protection, hence the weak zones were worn down and formed the hilly landscape.

Facts - weathering

Weathering is a process that mechanically and chemically breaks down rocks into minor particles such as stone, gravel and sand. The process is continuous and affects all rock surfaces.

The effect of the climate and the rock’s composition

The speed at which a rock weathers depends on the climate and also the composition of the rock.

Weathering goes slower in northern parts than in more southerly locations, where the climate is warm and humid.

Different minerals differ in their resilience against weathering. Also influencing is the texture, i. e. the rock microstructure, how the minerals are related, and the size of the grain. Since rocks are composed of minerals they withstand weathering to varying degrees.

Example of weathering

One example of weathering is when the warm sunshine of the day heats up the rock followed by cooling off during the night. Tension is built up that eventually causes breakdown of the rock. This type of weathering is most common in desert climates and may have affected the Ragunda area at the time when Sweden was located on more southerly latitudes in a hot climate 240 million years ago.