April 3, 1876.] -^^ ' [Price. 



diana, Illinois, &c., the uppermost strata of the drift is called the Loess or 

 Bluff foniuition." These " are the products of the last suhmergeuce, and I 

 have termed them the Lacitatrine Drift." Upon these "are scattered 

 boulders and blocks of all sizes of granite, greenstone, silicious and mica 

 slates, &c , &c., &c., generally traceable to some locality in the Eozoic area 

 north of the lakes." "The boulders are found on nearly all the drift- 

 covered area of the State; being carried over the summit of the water-shed, ■ 

 and reaching south nearly or quite to the Ohio, The margin of tlic boulder 

 area seems to mark the outline of the great ice-sheet at the period of its 

 greatest development ; but moat of tJie boulders strewed over this area, 

 appear to liam been deposited by anotlier agency, at a much later date." 

 They lie near the surface, often over purely laminated claj', "and hence 

 could never have reached their present positions through the agency of 

 glaciei-s or powerful currents of water. They must, therefore, have been 

 floated to their present resting places. The evidence is conclusive that they 

 were transported by icebergs, and hence I have called them the Iceberg 

 Drift," p. 4. 



Dr. Newberry gives 87 observations of a system of grooves contined to 

 the lake basin and the northwestern counties of the State, from which he 

 says "the prevailing direction of the stria is IQO south of west," and re- 

 marks "that in this portion of the State a series of glacial marks which 

 have a nearly north and south bearing, are obliterated by the stronger, 

 fresher, and more numerous grooves of which the bearing is nearly east 

 and west. As I have shown elsewhere, the striae which cover the highlands 

 and southern portions of the State were probably made by the continental 

 glacier which existed during the period of greatest cold, and which 

 had in Ohio a movement from north toward south and southeast ; 

 while the glacier which moved from east westward in the lake basin 

 was a local glacier of later date, and the one by which the excavation of 

 the lake basin was principallj' effected." 2 Obio, R. 10. 



"It seems that in the period of greatest submergence the larger part of 

 the summit of the water-shed was under water." "At this time a suf- 

 ficient depth of water existed in the passes of the water-shed to float ice- 

 bergs of considerable size, and as currents flowed through these passes, 

 some of the boulders scattered over Southern Oliio were probably trans- 

 ported by them." Five of these passes are noticed ; marked "by deeply 

 excavated channels, now more or less perfectly by great accumulations of 

 rolled and transported material, such as would be the natural product of a 

 copious flow of water, continued through ages of time, and gradually di- 

 minishing and losing its transporting power." p. 47. These out-lets car- 

 ried the waters southwestward into the seas or lakes of the great Mississippi 

 valley. The Niagara River and Falls then were not. p. 52, 



" The boulders belong almost without exception to the chrystaline and 

 igneous rocks that are found in situ only to the north of the great lakes." 

 p. 26. None are from east Canada or Labrador ; but nearly all "can be 

 traced to places of origin in localities north and northwest of Ohio. " p. 27. 



PKOC. AMER. PHILOS. SOC. XVI. 97, 2g 



