Landsat image of the Kongakut River Delta, North Slope, Alaska
The surface morphology of the northern slope of the Brooks Range (North Slope) from the Canning River, Alaska, eastward is dominated by a series of large alluvial fans and braided streams floored by coarse alluvium. On the basis of the absence of sediment on the seasonal sea ice after spring flooding, the measured stability of fan fronts during a 30-year period, and the scarcity or absence of Holocene marine sedimentary deposits seaward of the fans, we conclude that the fans are not prograding now nor have they been prograding at any time during the Holocene. In numerous areas, surficial fan alluvium terminates on land at or below 2-m-thick glaciomarine deposits. These deposits, the Flaxman Member of the Gubik Formation, formed during the latest major interglacial transgression (oxygen-isotope Stage 5a) at about 85-80 ka. We therefore believe that the fans are still older. Our observations suggest that during the latest transgression and the following sea level high stand, the North Slope depositional environment and climate differed greatly from the present ones.
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Michael Diggles
Created on: March 7, 2000 (cad)
Updated on: February 14, 2007 (bwr, mfd)