Proceedings of the Ohio State Academy of Science 41 



the different agents which EngHsh and American geologists as- 

 signed as the cause of peneplains. The same influence of local 

 conditions was seen in the greater readiness of the geologists of 

 the Mississippi valley to accept the divisibility of the glacial 

 period. The work of Ulrich and Schuchert grows out of the ap- 

 peal which the paleontological richness of the Cincinnati rocks 

 early made to them. The illustrations of this principle are many 

 in all geology, both in that of recent time in America and in the 

 earlier days of the science, as everyone knows who has read 

 Geikie's Founders of Geology. 



The importance of American contributions to recent progress 

 I have not spoken of separately. This has already been well done 

 by Professor Rice in his paper, Tlie Contributions of America to 

 Geology. I need only state my belief that of the different sub- 

 jects I have treated in this paper, the influence of American 

 geologists has dominated in the following: the studv of land 

 forms, the subdivision of the Pleistocene, the recent interpreta- 

 tion of sedimentary rocks, and speculation on the larger problems 

 of geology, in what may be called the philosophy of geology. 



Finally I should like to call attention to the great part specu- 

 lative geology now plays in science. Great as has been the de- 

 tailed study in field and laboratory in the last quarter-century, 

 the part of geological speculation has been even greater. To 

 some minds this may not be a matter for congratulation. They 

 may prefer study of the facts without generalization, certainly 

 without speculation. The late Professor Lesley of the Penn- 

 sylvania survey was one of these. In his Final Stinimary, speak- 

 ing of what he considers unjustifiable speculation, he writes : 



"Our knowledge of details is so poor that all our general 

 statements are mere mutterings in sleep, or the incoherent 

 rhapsodies of fever. The world is a kaleidoscope ; at every touch 

 it turns a little, and the scheme of shapes and colors changes to 

 our eye. A malaria of the indefinitely complicated exhales from 

 every region of geology and attacks the wise and simple alike. 

 Happy the investigator whose intellectual constitution is not 

 ruined by it in the end. Foolish generalizer, who mistakes the 

 paroxysms of chill and fever in his own incompetent imagination 



