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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 56 (1972)

Issue: 3. (March)

First Page: 624

Last Page: 625

Title: Coastline Sedimentation in Tectonically Active Geosynclinal Basin, Glacial Outwash-Plain Shoreline of Northeastern Gulf of Alaska: ABSTRACT

Author(s): M. O. Hayes, R. L. Henry, C. H. Hobbs, III, F. J. Raffaldi, P. R. Hague

Article Type: Meeting abstract


The outwash-plain shoreline of southeastern Alaska consists primarily of 2 types of coastal morphologic areas: (1) places where outwash streams border the shore, and (2) beach-ridge plains. The outwash streams provide an abundant supply of sediment to the longshore drift system. Beach-ridge plains develop as a series of prograding spits, most of which indicate sediment transport from east to west. The spits trail away from the streams that originate at the termini of large piedmont glaciers, such as the Bering and the Malaspina. Once a stream channel is abandoned, or a new outlet is found, the beach-ridge plain is eroded back at the rate of several feet per year.

The beach processes are dominated by southeasterly storms which generate exceptionally strong longshore drift from east to west. The cycle of erosion-deposition on the beaches is similar to that of the New England coast; that is, the post-storm profile is flat to slightly concave upward, the beach recovers by the landward migration of a series of ridge-and-runnel systems, and the maximum constructional phase is a broad depositional berm. The cycle is shorter on the Alaskan coast, presumably because of greater storm frequency. The

End_Page 624------------------------------

large diurnal inequality of the tides has a striking effect on beach morphology, because wave energy is concentrated at 4 different levels during a 24-hour period.

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