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THE JOURNAL OF GEOLOGY.

are of comparatively rare occurrence, being apparently no more plentiful than in the body of the drift. The aspect of this group of moraines is so very different from that of the group which lies outside it, that it is thought not improbable that they are the product of a distinct invasion. No decisive evidence of a long deglaciation interval separating the two groups has, however, been discovered.

Summary. From the facts above presented the following stages of the glacial period seem sustained:

  1. A glacial stage during which the ice-sheet extended farther south in western Ohio than in any later stage. This stage will need subdivision in case a buried soil horizon in the midst of its deposits be well substantiated.
  2. A long stage of deglaciation marked by development of soil and by attendant oxidation, leaching and erosion of the drift sheet.
  3. A stage of silt deposition during which the highest points in south-western Ohio apparently became covered at flood stages. From evidence gathered elsewhere it seems probable that the silt deposition accompanied a glacial stage whose deposits are concealed in this region by later drift sheets.
  4. A glacial stage, during which the outermost well-defined frontal moraine was formed. The drift of this stage is concealed in eastern Ohio by the later moraines. Preceding this stage is an interval during which the valleys became opened again to such depth that the main streams, at the time of this later ice invasion, flowed at levels 200 feet or more below the level of the upland silt.
  5. A stage of deglaciation of considerable length as indicated by valley excavation.
  6. A glacial stage characterized by sharply indented morainic ridges, thought to indicate vigorous action. The ice-sheet reached about to the glacial boundary in eastern Ohio, but fell short many miles of reaching the boundary farther west.
  7. A glacial stage characterized by morainic ridges of smooth contour. This stage embraces the final disappearance of
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