South of Jotunheimen, the main Caledonian thrust separates the overlying Jotun-Valdres nappe complex (mainly Precambrian basement rocks with some Eocambrian sparagmites) from a parautochthonous phyllitelquartzite mass (Lower Palaeozoic) lying on an autochthonous Precambrian crystalline fundament. Events within the Jotun-Valdres complex predating the main thrust are: a Precambrian phase of regional metamorphism (amphibolite facies) and deformation, followed by heterogeneous shearing and sedimentation of sparagmites and an early Caledonian phase of intense, penetrative deformation effecting the lower part (sparagmites and some basement). Main Caledonian movement was restricted to a thin basal thrust zone and accompanied by flow in the phyllitelquartzite mass below it (greenschist facies conditions). A post-thrust NE-SW trending fault (Tyin-Gjende) is thought to mark the SE margin of the 'Faltungsgraben' in this region.