Loess Formations of the Mississippi Valley

Abstract

The loess deposits of the Mississippi Valley area are widespread and have been extensively studied. In the upper valley they have definite stratigraphic relationships to the drift sheets. From these relationships they are known to have a definite stratigraphic sequence, and their ages have been, in the main, closely determined. They show an eolian genetic relationship to source areas by their thickness, texture, structure, topographic position, and percentage composition of carbonates. Their eolian origin is also indicated by their faunal and, in places, floral assemblages. Some of the loess deposits also reflect the climatic conditions under which they accumulated and the rate of deposition with respect to rate of solution of carbonates. Where they carry plant fossils, the nature of the vegetation which was growing on the surface at the time of deposition is recorded. The stratigraphic sequence that prevails in the upper valley can be unmistakably traced into the lower valley to beyond Natchez. Mississippi, in all its principal attributes. The authors find no substantial evidence to support the "loessification" theory of R. J. Russell and H. N. Fisk or for the Pleistocene correlations and events which they postulate, based on their hypothetical mode of origin of the loess.