The Canadian Beaufort Sea is underlain by up to 12,000 m of Upper Cretaceous to Quaternary sediments. These sediments were deposited in a series of prograding depositional complexes containing fluviodeltaic, shelf, slope, and basinal clastics. At least 10 major regional unconformities within the Upper Cretaceous to Quaternary section are recognized. The 2 most pronounced unconformities developed in late Eocene and late Miocene times.

In the Beaufort-Mackenzie basin, the Upper Cretaceous to upper Miocene sediments were deformed primarily by gravity tectonics into large-scale diapiric anticlines and rotated listric fault-bounded blocks. Some reverse faulting, associated with mud diapirism, is evident in the western part of the basin. The late Miocene unconformity separates the deformed sediments below from the essentially undeformed, overlying Pliocene-Pleistocene strata.

Beneath the eastern Beaufort Sea, seaward of Amundsen Gulf and Banks Island, the Upper Cretaceous and younger strata thicken abruptly basinward across a hinge line developed at the edge of the Arctic platform (mostly composed of pre-Mesozoic strata). The Upper Cretaceous to Quaternary sedimentary prism along this part of the continental margin is not disrupted by diapirism or listric faulting; in fact it is relatively undeformed, with only minor normal faulting in the older part of the prism.

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