Lying on the latest glacial till in eastern Minnesota are found different varieties of eolian deposits, such as lag gravels, dune sands, and loess. The last named material lies on the higher lands, which are usually the thicker morainic accumulations, and is rarely more than from a few inches to one or two feet in thickness. On the other hand, considerable formations of dune sands and associated lag gravels lie on the leeward side of the streams.
These deposits are frequent not only in eastern Minnesota but in the bordering districts of adjacent states. Inasmuch as no descriptions are seen of such accumulations, the inference is that they have been regarded by the many glacialists who have worked in this region as glacial in origin and therefore described as modified drift; that is, as a water deposit rather than dune sands of eolian . . .