November 13, 1896.] 



SCIENCE. 



711 



L. Arey to exist here in a well defined de- 

 velopment. 



The exploitation of the Lower Helder- 

 berg, a typically eastern New York forma- 

 tion and fauna, through this western dis- 

 trict, brings out much important knowledge 

 as to its relations with the under and over- 

 lying faunas, and this region will play an 

 important role in the determination of 

 serious questions bearing upon the geolo- 

 gical age of the Lower Helderberg group 

 and the integrity of the New York Series. 



The Portage group also presents a num- 

 ber of interesting problems. Its fauna in 

 the original sections is an exotic one, the 

 most complete replica, in the American 

 paleozoic rocks, of an European fauna. It 

 may almost be said that here in New York 

 it had neither predecessors nor successors. 

 But eastward in the State the fauna 

 changes, and Portage time is represented 

 by a rock series whose fauna has nothing 

 in common with that in typical Portage 

 sections, but which has been derived, and, 

 indeed, is often difficult to distinguish 

 from the Hamilton fauna, which preceded it. 

 And within the same time element further 

 east, a portion of this fauna is again re- 

 placed by the meager, shallow and brackish 

 water fauna of the Oneonta beds. Along 

 such lines as these pertaining to the histor- 

 ical geology and the evolution of the life of 

 the Fourth District, the labors of Prof. Hall 

 have been followed by those of Professors 

 Henry S. Williams and Charles S. Prosser, 

 whose results have been most suggestive 

 and important ; and others have cooperated 

 in the increase of this knowledge. Prof. S. 

 G. Williams, Luther, Eingueberg, Lincoln, 

 Bishop, Mixer, Harris, Pohlman, Grote, 

 Pitt and some others. 



The facts recorded in the report of this 

 District concerning its surface contour, the 

 later changes of topography, the distribu- 

 tion and mode of accumulation of superfi- 

 cial deposits, the presence of buried valleys, 



and other data especially inviting the 

 glacialist and geomorphist, are in suggestive 

 abundance, and it is no wonder that re- 

 markable and beautiful results have been 

 obtained from this region during the later 

 rapid growth of these special lines of geo- 

 logic research. Witness the work of Gil- 

 bert, Spencer, Dryer, Fairchild, Taylor and 

 Leverett, and that old geological clock, Niag- 

 ara Falls, which has been the center of 

 such many-sided discussion. The elaborate 

 account of it, its topography and changes, 

 published by Prof. Hall, in 1843, has been 

 regarded as of such fundamental value thaHj, 

 more than fifty years afterward, it is re- 

 printed in its entirety by another depart- 

 ment of the State government. 



We have come to a period in the history 

 of geologic investigations in the old Fourth 

 District of New York where nice questions 

 bearing upon the significance of variations 

 in faunas, their origin, dispersion, taxon- 

 omy and chronology are pressing to the 

 front. Their solution may involve the 

 weakening of the conventional division 

 lines upon which we have so long de- 

 pended, but which are only confessions of 

 faulty knowledge. In the study of such 

 questions the labors of Prof. Hall have 

 given to the State of New York a supreme 

 advantage. Only with their solution will 

 come accurate geologic maps and a precise 

 knowledge of our geology. 



As we are accustomed to look back into 

 these paleozoic faunas for initiatory types 

 of organic life whence depart into the later 

 history of the earth a multitude of diverse 

 organic expressions, so we find in the orig- 

 inal survey of the Fourth District the ker- 

 nel of all later work along the lines indi- 

 cated, the suggestion of the completed geo- 

 logy of the State of New York. 



Albany, N. Y. John M. Claeke. 



Prof. Clarke's address was illustrated by 

 various maps, particularly the two sheets 



