Sveafallen, Naturreservat

The Sveafallen nature reserve is a well-known key area for geological research on the former outlet of Lake Ancylus during the latter part of the Ice Age. Today, the area is forested, but traces of the melting of the ice can be seen in the form of giant pots and boulders.

History

When the ice sheet retreated 10,000 years ago, large parts of present-day Sweden were under water. A large inland sea, the Yoldia Sea, twice the size of today's Baltic Sea, covered large parts of Svealand and half of Finland. The land that had been submerged under the 3 000 meter thick ice gradually rose. This uplift, which continues today, raised the land surface by 160 meters in the Degerfor area. As the land rose, the Närkesundet strait was narrowed. Eventually, only a narrow strait remained, known as the Svea River. It flowed via Lake Vänern into Skagerrak and Kattegat.

Different theories

The great geological importance of the area was first discovered in the 1920s by Professors Munthe and von Post. The early research claimed, among other things, that due to a marked difference in level between Lake Ancylus and Skagerrak and Kattegat, powerful waterfalls arose in the area. Comparisons were made with today's Niagara Falls and it was suggested that the Svea Falls may have been three times as large. These assumptions have since attracted many tourists. Later research, including by Professor Fredén in the 1960s and 1970s, suggested that there was no major difference in level between the seas and that there were therefore no actual waterfalls. However, for a time there was a narrow strait here at Degerfors, where large amounts of water flowed.

Traces of giants?

In Sveafallen there are a number of so-called giant pots. The smallest are just a few decimeters wide bowls in the bedrock, while the largest are 1-4 meters wide and up to 8-10 meters deep. So far, over 200 pots have been found, but every year new pots are discovered. But how did these cavities in the rock come about? For our ancestors, who had never heard of an ice age, big and strong giants were at least as good an explanation. The large holes were thought to be where the giants had cooked their food. Perhaps you have seen large boulders here and there in the area? Today we say boulders, in older times they were called giant boulders. According to old legends, the giants disliked the sound of church bells and therefore threw large stones in the direction where the noise was heard. Today we know that these blocks are located here and there and have been placed by the last ice sheet. Like a planer, the ice slid along and broke off pieces of the bedrock, which it then carried away, sometimes for very long distances.

Giant pots

Most of the pots in Sveafallen were formed when a kilometer-thick ice sheet covered the area. Meltwater then rushed down into the cracks and grooves of the ice to form ice rivers under the ice. According to older theories, it was a so-called runner stone that used the water currents to dig out these pots. Today, geologists point to another main cause, a process called cavitation. The flowing water was affected by high pressure from the ice. At a rocky outcrop or other obstacle, the velocity of the water stream increased, only to decrease abruptly after the obstacle. The bubbles in the water, formed by gases, dissolved when the speed of the water current suddenly decreased. The force generated by the dissolving bubbles was like a hammer digging into the rock. Rocks and gravel in the rushing water have since helped to hollow out and polish the pots.

Stream gutters

Five stream channels can be seen in the nature reserve. Geologists do not know exactly when these were formed. Probably already before the period when the land uplift created the narrow strait where the waters of the Svea River drained Lake Ancylus. But it is certain that these water masses have continued to shape and grind down these channels. The most obvious channels are Domedagsdalen and Bergtjärnsrännan. Domedagsdalen is the deepest channel and has on its western side a steep cliff wall with a highest point of 17 meters above the ground. In the southern part of the reserve, at Bergtjärn, is Bergtjärnsrännan. There, a high and vertical cliff juts out over the tarn. This area also contains the watershed (with its lowest point in the area) between the Baltic Sea and the Skagerrak.

Nature and vegetation

The natural environment at Sveafallen consists of coniferous forest, dominated by pine, growing on rocky ground. In some parts of the area, the forest is managed through active measures to keep it open so that there is a good view and overview of the area. The rest of the forest is left to develop freely. Rock slime grows sparsely on some rocky areas. There is also a safe place for knotweed to grow in the vicinity of the Gryt area. There are also some wooded swamp areas in Sveafallen. In the southern part of the reserve, the ground and rocks are covered with moss. There you can experience forests reminiscent of John Bauer's troll forests.

Accessibility

The area in Domedagsdalen is reached via a paved path from the ironworks parking lot, just north of the valley. There are accessible picnic tables and information signs.

Hiking trails

There are hiking trails of varying length and difficulty in the nature reserve. The short trail through Domedagsdalen is about 1.4 kilometers long and easy to walk. The longest around Bergtjärn and the watershed point is about 5.3 kilometers long. In its southern part, it is hilly and more difficult. The hiking trails and potholes are marked with orange markings on trees and rocks. If you start from the large parking lot at Kulturcentrum Berget, in the far north, you will reach the information and starting point of the hiking trails after about 50 meters.

Barbecue area

Fires are not allowed in the nature reserve, but just north of the reserve there is a rest area with the possibility of grilling. The rest area is managed by Degerfors municipality.

Take the bus to the reserve

Länstrafiken buses 502 and 593 stop just north of the reserve, at the Sveafallen stop.

Sign interpreted information

Geological sights