Abstract Alaska faces the Canada Basin of the Arctic Ocean along an arcuate continental margin, gently concave to the north, that stretches unbroken from the Mackenzie Delta, near 137°W to North wind Ridge of the Chukchi Borderland near 162°W. (Marine geographic features mentioned below can be found on Plates 1 and 11 of Grantz and others, 1990a.) This margin, with an arc-length of about 1,050 km, marks one side of a continental rift along which the Canada Basin opened by rotation about a pole in the Mackenzie Delta region during middle Cretaceous time. The rift-margin structures, which lie beneath the inner shelf and coastal plain in the eastern Alaskan Beaufort Shelf and beneath the outer shelf in the western Beaufort and Chukchi Shelf, are now buried by a thick middle Lower Cretaceous to Holocene progradational continental terrace sedimentary prism. We divide the Arctic continental margin of Alaska into three sectors of strongly contrasting geologic structure and physiographic expression. In the Barter Island sector (see Figs. 3 and 4) the structure is dominated by the effects of Eocene to Holocene convergence and uplift, and the continental slope is upwardly convex; in the Barrow sector the structure is dominated by the effects of middle Early Cretaceous rifting and continental breakup, and the continental slope is upwardly concave; and in the Chukchi sector the structure is controlled by an easterly trending middle Early Cretaceous rift, and the continental slope abuts the Chukchi Borderland. Physiographically, the Alaska continental margin is expressed by the Alaska continental rise and slope

Abstract Alaska faces the Canada Basin of the Arctic Ocean along an arcuate continental margin, gently concave to the north, that stretches unbroken from the Mackenzie Delta, near 137°W to Northwind Ridge of the Chukchi Borderland near 162°W. (These and other regional geographic features mentioned below can be found in Plates 1 and 11.) This margin, with an arc-length of about 1,050 km, marks one side of a continental rift along which the Canada Basin opened by rotation about a pole in the Mackenzie Delta region during middle Cretaceous time. The rift- margin structures, which lie beneath the inner shelf and coastal plain in the eastern Alaskan Beaufort Shelf and beneath the outer shelf in the western Beaufort and Chukchi Shelf, are now buried by a thick middle Lower Cretaceous to Holocene progradational continental terrace sedimentary prism. We divide the Arctic continental margin of Alaska into three sectors of strongly contrasting geologic structure and physiographic expression. In the Barter Island sector (see Figs. 3 and 4) the structure is dominated by the effects of Eocene to Holocene convergence and uplift, and the continental slope is upwardly convex; in the Barrow sector the structure is dominated by the effects of middle Early Cretaceous rifting and continental breakup, and the continental slope is upwardly concave; and in the Chukchi sector the structure is controlled by an easterly trending middle Early Cretaceous rift, and the continental slope abuts the Chukchi Borderland. Physiographically, the Alaska continental margin is expressed by the Alaska continental