A reflection seismic investigation suggests synsedimentary subsidence for the western part of the Jameson Land Basin. Two seismic sequences document the strong erosion which took place during the Cretaceous/Tertiary. Further erosion resulted from the development of several glacial phases in the Quaternary leading to a very thin (below 12 m, in shallow areas below 5 m) cover of Quaternary sediments. -from Author