Bathymetric and seismic surveys of the trough across the continental shelf of Baffin Island at Broughton Island indicate that there were four stages in its development. The first involved deposition of Cretaceous and early Tertiary marine sediments before and during formation of a graben associated with the opening of Baffin Bay. With the uplift of Baffin Island, extensive deltaic deposits at the distal end of the trough were laid down in the second stage. These deposits are thought to represent the products of a river system raised much above grade, flowing in the trough and the fiords to the southwest, and depositing in a sea with a relative level 300–400 m below present. In the third stage during Pliocene–Pleistocene glaciation, the proximal regions of the trough were eroded to more than 700 m below present sea level. Lateral moraines indicate the extension of ice to the edge of the continental shelf, although the relatively small amount of erosion in the distal region suggests that the ice may have been partially floating. Glaciomarine and marine sedimentation following glaciation is the final stage in the evolution of the trough.