Overall shapes of lands and seas in northeastern Canada are the result of tectonic events that were part of continental drift. Breakup of this region began as early as Late Cretaceous time, and continued to post-Oligocene or post-Miocene time. Structural lows formed seaways and structural highs formed islands. Crustal thinning beneath the seaways produced isostatic arching that was broader than the seaways and elevated the margins of lands. The initiating tectonic processes have ceased in this region, but the pattern persists today.Distribution of glaciers on Baffin Island and Greenland is such that a narrow high coastal belt separates the glaciers from the seas. This pattern is probably due to isostatic forces resulting from crustal thinning as Baffin Island and Greenland drifted apart. It is suggested that Greenland is surrounded by high land and has an interior ice-filled basin, mainly because it is surrounded by rifted coasts on which this process of crustal thinning and isostatic compensation occurred.A similar pattern of seaward highs exists along the rifted north coast of Eurasia. Regions where this occurs include Scandinavia, Spitsbergen, and the northern coasts of Siberia and Novaya Zemlya.