It is argued on the basis of structural, stratigraphic, and sedimentologic criteria that Princess Margaret Arch developed during the principal phase of Eurekan thrusting and folding and therefore is no older than Middle Eocene. Sub-Eureka Sound Group unconformities on eastern Axel Heiberg Island are not associated with uplift on the eastern flank of this arch but are related to erosion of Mesozoic Sverdrup Basin strata over local evaporite diapir domes and ridges. Considerable disparity exists between levels of erosion on the flanks of the arch and the level of erosion along its axis, which cannot be explained by pre-Eocene uplift. Sedimentary facies and textural and petrographic characterisitics of Eureka Sound Group strata do not reflect proximity to an arch. Palynomorph assemblages in the west-derived, syntectonic Buchanan Lake Formation (Middle Eocene) contain reworked latest Cretaceous spores and pollen that were derived from Eureka Sound Group strata originally located on or close to the arch axis.Eureka Sound Group sedimentation in the Axel Heiberg Island – west Ellesmere Island region took place in a single, contiguous basin, rather than in smaller basins that were separated by ancestral Princess Margaret Arch.