Eolian Deposits of Alaska

Abstract

EOLIAN deposits of Pleistocene to Recent age are recognized in all major regions of Alaska (see Fig. 1). Lack of economic incentive and of suitable base maps or air photographs have in the past precluded much detailed work on such deposits. Further, complexities produced by growth of vegetation , reworking by streams, and, particularly in areas of permafrost, by frost action and mass wasting processes, tend to mask, assimilate, modify, or remove eolian materials as they accumulate. Consequently at present only a small proportion of the eolian deposits can be shown on a map and relatively few data are available on their morphology, stratigraphy, and genesis. This paper is an attempt to summarize these data, at the request of the US. National Research Council Committee for Study of Eolian Deposits in North America. The writer has visited all the major areas of eolian deposits described here and has incorporated into the text and map his own ideas or interpretations rather than utilizing.only those of other workers. He acknowledges gratefully the unpublished information and comments received from each of the persons listed on Fig. 2, who have carried out detailed studies of the areas shown. Many ideas expressed, for which individual acknowledgment is difficult, originated with them. Special mention should be made of the valuable summaries by Clyde Wahrhaftig and David M. Hopkins, parts of which a= quoted verbatim. David M. Hopkins, W. A. Rockie, and Troy L. Pkwk, in particular, critically reviewed the entire manuscript. For convenience, the eolian deposits are discussed in three major groups, in each of which the physical setting and types of deposits and their genesis are similar. These groups are: Coastal plain of northern Alaska; Areas associated with glacial streams; and Coastal margins. These groups grade into one another and, obviously in a region as large and as complex as Alaska, many variations exist from one deposit to another. The areas associated with glacial streams have been subdivided because of their diversity, enormous area Involved, and lack of information. The writer believes that only higher parts of mountain ranges and local areas in the lowlands, together comprising less than half the territory, have escaped some eolian deposition. However, eolian materials over a wide area either were very thin and have been. removed, or else have been masked or assimilated by other sediments. In southeastern Alaska eolian deposition is confined to the neighbourhood of braided glacial streams. Fig. 1 shows only those areas in which eolian materials are known to occur; in many districts the extent of the eolian materials is believed to be greater than that shown. ~"