I'lU-cJ -J^^ [March 3, 17 & 



An inquiry here arises that if floating ice must bare been the cause 

 of all tlic drift and i-rratics, why shouUl not tlie same cause have produced 

 the boulder clay '! The floating ice could as well do it, as it ground over 

 the le:lges of rocks, as an Arctic glacier and tlie water could better si)read the 

 clay as it is found. Such a supposition would obviate a resort to the great 

 ice-shoct for explanation, and avoid other ditficulties to be noticed. It is 

 certainly an immense conception of an abnormal cause to explain a limited 

 effect, that seems to have already had its sufticient and acknowledged solu- 

 tion in the cause of every other stratum of the drift. 



It is said by Dr. Newberry (2 Ohio Rep. 29), "That the boulder clay 

 was not deposited beneath the glacier, as sometimes stated, is apparent fi'oni 

 :the fact that it covers the glaciated surface on wliich the ice rested, in a 

 ^sheet sometimes a hundred feet in thickness. It must, therefore, have ac- 

 •eumuhtted at the uiarrjiii of the glacier." As the boulder clay is very 

 widely spread, as well as often of a great depth, the more natural inference 

 would seeiu to be that it was spread by the waters, as ground from the 

 rocks by floating ice-rafts, and afterwards yet more dispersed by the ocean 

 currents. But the witnesses do not alwavs agree with themselves or with 

 each other upon this subject. 



The 2 Volume of Ohio Rep. in its Chapter L., contains views at vari- 

 ance with tlie theory of "the glacier," contributed by Mr. E. B. Andrews. 

 He says Professor Hopkins expresses the belief that the boulders found on 

 highlands of the 2d Geological district, Avcre transported by floating 

 ice- rafts, "and not bj' a vast, continuous northern glacier," and that drift 

 materials were carried down to the lower Mississippi district. And Pnifessor 

 Hilgard thi-uks that "the ])lienomena observed in the Southern States 

 are but the Jiecessary consequences and complements of the drift phe- 

 nomena of the North," and says it is time "that the Ohio should cease to 

 be proclaimed as the southern limit of the drift." p. 451. Mr. Andrews 

 speaking of the southeastern part of Ohio says, we have seen "there is no 

 evidence that the pre-glacial or ante-drift surface was essentially different 

 from what it now is. If there was a climate so arctic in character as to 

 allow of the extension of a sheet of ice immensely thick almost to the 

 Ohio River, we should expect thai the same cold climate would necessitate 

 glacialion in the Allegheny Mountains, but a short distance south of the 

 Ohio, where no traces of glaciers have been found. The average altitude 

 of the Allegheny range is 3,000 feet. If, on the other hand, the cold were 

 produced by marine currents coming down from the Arctic region, it would 

 have the sharp limitations characteristic of such currents at the present 

 day." "Local glaciers are freely admitted to have existed on the higher 

 grounds adjacent to the icy northern currents." p. 449. Mr. Andrews 

 quotes the strong views of the Duke of Argyle, President of the Geological 

 Society of London, against the glacial sheet, as satisfactory, p. 450. 



In the Geological Survey of Illinois, of 1873, the northwestern section 

 is described by James Shaw. He .says, " That vast glaciers of ice once ex- 

 tended over large portions of North America is now univensally concedetl. 



