Halleberg

Table mountain by lake Vänern in western Sweden

Halleberg is a table mountain by lake Vänern in Vänersborg Municipality, Västergötland, Sweden. Halleberg, part of which protrudes into Lake Vänern is separated in the south by about wide valley from the adjacent Hunneberg (also a table mountain). The northern part of Halleberg called Hallesnipen.

Hallberg has an average height of about above lake Vänern, or 134 feet (41 m) above sea level; the highest point is above sea level. Halleberg consists of Cambrian, Ordovician and Permian rocks. The Palaeozoic rocks are deposited directly on the crystalline peneplain bedrock, which in this range consists of göta granite. The Cambrian sedimentary rocks are sandstone and alum shale. The sandstone layer is on average thick. Above this there is then a thick slate which in turn is covered by about of alum shale. The Ordovician is represented by a calcareous slate. During the Permian diabase pushed between the still present and since eroded Ordovician layers, which lay as a protective cover over the softer sedimentary layers under it and thus protected the mountain from erosion. The diabase on Västgötabergen is known locally for staircases.

Anthraconite, alum shale and diabase has previously been mined in several places on the mountain.

Around the foot of the Halleberg are elongated scree of large stacked, sharp edged boulders. In a few places, there are so called steps, where there are roads or paths up the mountain. The vegetation on the mountain plateau is dominated by spruce and pine, and the expanse of bog, while on scree lower parts are more species. In contrast to Hunneberg, on Halleberg there is simply lake Hallsjön, three kilometer long but narrow. On Halleberg is the Ecopark Halle Hunneberg (comprising the Halle och Hunnebergs platåers naturreservat and the Halle och Hunnebergs branters naturreservat).

Halleberg is also Scandinavia's largest hillfort (about ). It is almost completely naturally fortified by the mountain's steep slopes, large stone ramparts being primarily at the Storgårdsklev steps in the southwest. There are three stone ramparts, with a total length of , of which the longest is about long and high. Small ramparts have in passable gaps, for example at the Lilleskog and Björkås trappa staircase. The hill fort was built during the Migration Period of the 3rd 4th centuries. It was a refuge during the Swedish Danish wars of the 15th 17th centuries, for example during the Gyldenløve War in 1676, but also during Gustav III's Russian War of 1788. The Danes only managed to conquer the castle once, in 1612. During the Basse War (Bassefejden in Swedish) of 1490–1510, Halleberg was besieged for seven years. The place name (in about 1325 Haal), had previously only a hall, including a 'rock face' entrance hall, a 'cliff' or similar.