Part 1 of Essay
Abstract The sediments and the trace fossils of the record the advance passage of a major eolian sand sea. Both invertebrate and vertebrate traces indicate that the substrate was, was for the most part, very dry though it was clear that light rainfall or dew periodically moistened the dune surfaces. Although we know that ....

Part 2 of Essay
.... that once extended north into Montana. During the last ten years, a number of studies on modern and ancient sand seas, or ergs, have increased greatly our understanding of eolian bedform dynamics. Additionally, we can describe trace fossils in the Coconino and relate them to the physical environments of deposition. This provides us with more comprehensive reconstruction of the erg environments. Although the cliff-forming nature of the formation can present certain logical problems, the exceptional three-dimensi ....