144 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 indi- 

 cated by valley excavation. 



6. A glacial stage characterized by sharply indented mor- 

 ainic 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 



