The emplacement of large, far-traveled Nappe complexes or thrust stacks are common features of A-type collisions. Recently, extensional processes have been shown to be active, at least during parts of the collision process. This project will examine the deeply eroded roots of the Scandinavian Caledonides to study the relations between a far traveled nappe complex and continental plate subducted beneath. Mapping and laboratory work on the kinematics within this zone, the geological relations between the allocthon and underthrust Baltic Shield and the PTt evolution of the underthrust Baltic shield are the main focus of this project. Results are expected to determine the involvement of the Baltic basement below a thin zone of basement thrusting and to test the extent of extensional displacement of the allocthon.