There are deep marginal sedimentary basins in the Labrador Sea extending to the region of Davis Strait. In contrast, the central part of the Sea shoals toward Davis Strait. The difference is explained by the central part of the Sea being formed while the Davis Strait hot spot was active, producing increased vulcanism and crustal thickness. The sea floor along the margins was produced before the hot spot became active about 60 m.y. ago, so has normal crustal thickness and thus normal basement depth.