The bedrock of the Kjølhaugan area is subdivided into the Seve-Köli Nappe Complex overlain by the Trondheim Nappe. The former comprises mica schists and amphibolites (Seve) overlain by garbenschiefer (Köli). The upper (western) unit is a segment of the Trondheim Nappe Complex. It overlies the Seve-Köli Nappe Complex in the western limb of the Sylarna-Riksgränsen Antiform and is composed of metamorphosed volcanic and sedimentary rocks. The upper units of the succession have been investigated in detail in the vicinity of Mount Kjølhaugan and a new stratigraphy has been established based on re-interpretation of the structure. Graptolite-bearing black phyllites (Llandoverian age) of the Slågån Group occur in the vertical to overturned (60°W) limb of the Liafjellet Syncline, and are overlain to the east by the turbidites of the Liafjellet Group. The Slågån Group passes westwards, downwards into the inverted stratigraphy of the Kjølhaugan Group, which in turn passes down into the Sulåmo Group with the basal volcanogenic Lille Fundsjø conglomerate.