CONCEPTIONS REGARDING THE AMERICAN DEVON I C 1 



BY JOHN M. CLARKE 



This theme has seemed to me appropriate to the present occasion 

 because, primarily, of Professor Kayser's positive influence upon 

 the accepted interpretation of the Devonic system in the Western 

 Hemisphere and, in a broader sense, for his long and intimate con- 

 cern with the various aspects of this great period in the history 

 of the earth. 



It is thirty-six years since the publication of Kayser's important 

 treatise on the Lowest Devonic Formations of the Hartz Mountains, 

 and this, more than any other single work, inaugurated a recon- 

 struction of ideas concerning the scope of the Devonic system ; in 

 so doing, it created new problems and inspired investigations into 

 a wider field. Thirty-six years ago the writer of this paper, truly 

 a native of the Devonic, was fresh from college and full of en- 

 thusiasm over the study of this formation. Throughout the stretch 

 of years since then, both have labored continuously over the 

 Devonic problems, for much of the time in close and sympathetic 

 touch, the younger man receiving from the elder, in information, 

 suggestion and inspiration, debts which can be repaid only in service 

 to a common science. 



The State of New York, which has been the writer's port of 

 departure into this field, is very properly designated a Devonic 

 state, for more than one-half its area is covered by the rocks of 

 the period, and the succession of its members from base to summit 

 comprises a record whose pages are almost intact and effectively 

 illustrate the variant happenings of the time. In America we were 

 long in the way of endeavoring to square all the Paleozoic forma- 

 tions of the country with the New York standard column. The 

 work of the founders of the " New York Series of Formations " 

 in establishing their classification, nearly seventy-five years ago, 

 was well done, but the amplification of our knowledge has now 

 clearly shown that in all elements of the Paleozoic except the Devonic 

 (the Cambric, Lower and Upper Siluric and Carbonic), the New 



1 The distinguished career in geological science of Professor Emanuel 

 Kayser of Marhurg was to have heen specially celebrated on his seventieth 

 birthday, 1915, hy the publication of a Festschrift of essays by his 

 colleagues and students. For this purpose and occasion the essay here given 

 was prepared. 



