The main scientific goal with this thesis is to study the configuration of the main Caledonian geological structures within the Lower Silurian succession, with emphasis on back-thrusts at Sundvollen, Ringerike in southern Norway. This involves determination of the relationship between main- and subsidiary thrusts and folding in context to the development of the Ringerike area.Four separate deformational phases connected to the study area are identified based on analysis of the structural geological data. Phase 1 represents the oldest structures, whilst phase 4 represents the youngest. Thrust faults and folds connected to deformational phase 1 are associated with bedding-parallel shortening. The development of tight- to isoclinal, disharmonic folds with upright axial planes is defined as deformational phase 2. Structures connected to deformational phase 3 are foreland-directed thrust faults and large, open and upright folds with wavelengths in the order of hundreds of meters. The orientation of the maximum stress axes indicated by structures associated to phase 1 are generally consistent with what is known for the regional transport in the Oslo Region. The transport directions displayed by the structures comprising phases 2 and 3 are consistent with the main SSE-directed tectonic transport direction displayed in the Oslo Region (e.g Gabrielsen and Larsen in press). Deformational phase 4 comprises back-thrusts. Structures connected to this phase are low-angle thrust faults and fault-propagation-folds. The transport direction of the faults shifts gradually from N-NNW in the southern part of the study area to WNW-NW in the northernmost part. The generally gentle deformational style, characterized by large open folds as displayed in the study area, is consistent with the general structural style in the upper Cambro-Silurian succession in the Oslo Region (Morley 1987a). Back-thrusts are however the most dominant of the exposed thrust faults in the study area. All structures are situated in the Lower Silurian succession at Ringerike. Therefore are phases 1-4 formed in response to the Scandian phase, which corresponds to the main Caledonian deformation (e.g Roberts 2003).