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Abstract

Continental subaerial (i.e., non-aquatic) deposits can be conveniently grouped into two main categories: eolianites and soil zones. A common misconception regarding such deposits is that they are devoid of fossils. Although their paleontologic record is indeed meager, distinct suites of trace fossils are present that ultimately may prove useful as diagnostic tools in identifying these environments in the rock record.

By far the most extensive geologic record of continental non-aquatic environments is that characterized by eolianites (i.e., sand dune deposits). Modern eolian sediments are associated with two major areas: (1) sandy deserts (or ergs) and (2) coastal dunes. Their identification depends primarily on the recognition of features that can be attributed to the transportation, deposition and erosion of sediment by wind.

Recent reviews on the physical characteristics of eolianites (Bigarella, 1972; Collinson, 1978c; Walker and Middleton, 1977; Ahlbrandt and Fryberger, 1982 have suggested that the following features may be diagnostic of wind-derived deposits: (a) large-scale, high-angle cross-strata (up to 35 m thick), which commonly are planar-tabular or trough to wedge-shaped; (b) high ripple indices with large bedforms showing a consistent ripple index from base to top; (e) sedimentary structures related to the process of sand avalanching down dune slip faces; (d) minor sedimentary features, including raindrop imprints, vertebrate tracks and deformation of lee-side laminae; (e) intercalated interdune deposits and/or poorly sorted lag deposits along erosional bounding surfaces; (f) frosting of sand grains; (g) large and small-scale deformation features; (h) characteristic light and heavy mineral separation ratios.

Although such sedimentologie features

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