The Canadian arctic islands represent a Tertiary fluvial landscape developed on a contiguous landmass subsequently fractured by block faulting. Nonetheless, some theoretical models invoke pervasive high-latitude ice sheets and continue to misattribute the faulted landscape to glacially scoured river valleys. Quaternary fieldwork on northern Ellesmere Island suggests that these models are inappropriate for high-latitude ice sheets and should be abandoned. If there was ever a regional ice sheet over arctic Canada, it likely occurred on a prefaulted, contiguous landmass that had a more temperate climate than at present, possibly during the late Tertiary. After block faulting, the marine channels permanently prevented the ice from inundating the landscape it once crossed. Tectonics, and not climate, have led to a fundamental change in glacial style. This block faulting also may have played a role in terminating the late Tertiary boreal forest (to ∼80°N) by establishing cold marine channels that diminished the continentality of the once-contiguous landmass. For a thorough understanding of the Canadian arctic landscape, future research should determine the continuity between the Tertiary and Quaternary paleoenvironments. The unknown ages of the fiords and interisland channels are of primary importance.

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