The area of NW Wedel Jarlsberg Land south of Bellsund (Spitsbergen), between Dunderbukta in the west and the Berzeliustinden mountain group in the east, consists of five fault-bounded blocks: (1) the Renardbreen Block (Middle–Late Proterozoic basement rocks), (2) the Chamberlindalen Block (Late Proterozoic basement rocks), (3) the Martinfjella Block (Late Proterozoic through Early Ordovician basement rocks), (4) the Berzeliustinden Block (Late Proterozoic and Early Ordovician basement rocks covered by Late Palaeozoic–Tertiary platform deposits), (5) the Reinodden Block (Late Palaeozoic and Mesozoic rocks). The paper presents an outline of lithostratigraphy (Middle/Upper Proterozoic–Lower Ordovician: Hecla Hoek Succession) and architecture of the Caledonian basement in which several thrust-sheets and thrust-folds have been recognized. It also discusses some aspects of Tertiary overthrusting, faulting and rotation with affected the basement rocks and remodelled its Caledonian architecture.

The Slyngfjellet Conglomerate which occurs at the base of the Upper Proterozoic Sofiebogen Group in South Spitsbergen had formed predominantly as a debris-flow deposit, with subordinate contribution by fluvial and probably lacustrine sediments. There is no evidence for glacial conditions at the time of formation of the conglomerate, the latter being much older than the latest Proterozoic Varangian glaciation tillites elsewhere in Svalbard. The Slyngfjellet Conglomerate originally filled buried valleys eroded by rivers in block-faulted and uplifted western margin of the Mid-Proterozoic Torellian Basin.