Gloppedalsura is a scree consisting of boulders piled atop a terminal moraine. The landscape underwent major changes more than 10.000 years ago when the glaciers melted away from Gloppedalen. For a while, a huge terminal moraine dammed up the Hunnedal River, blocking its course toward Veen and Vikesa. A lake was formed in the Byrkjedal Hollow as a result. The terraces in Byrkjedal. 240 meters above sea level. bear witness to this moraine – dammed lake.

Freezing and thawing processes suddenly caused an enormous amount of rocks and boulders to slide down the mountain’s southern slope, forming a 100 – meter – thick scree atop the termmal moraine. The Hunnedal River and the water in the Byrkjedal Holiow now had to find a new outlet. so it dug itself a ravine from Byrkjedal toward Gilja. the Gilja Gorge. Most of the debris in the Byrkjedal terraces was carried off by the river to Dirdal.

War activities in Gloppedalsura in April 1940
Gloppedalsura was the site of heavy fighting during World War II. Two German companies attacked Gloppedalen from Veen on 22 April, The scree, with its boulders and passageways. served as a stronghold for the Norwegian forces. It also provided good cover during air attacks
The Norwegian soldiers slept in freezing weather the night before 22 April, They had previously blown up the road at Vinjevatnet in several places and blasted a breach across the frozen lake. German planes flew regular missions over the scree. On the eve of 22. April the Germans launched a major attack, but they came no closer than 25 meters from the Norwegian positions. The Norwegians‘ supplies were disrupted by the air attacks.
That night the German troops silently descended the Dirdal mountainside, catching the Norwegian forces by surprise and wounding Major Brandt. The major and his entire force in Dirdal capitulated. Colonel Spörck then realized the futility of continuing the campaign against the Germans in Gloppedalsura. The Norwegians lost one man. The Germans suffered heavy losses.

Source: Information board on site