AMERICAN GEOLOGY DECADE OF 1840-1849. 883 



had assumed their proper importance for him, he would have resented an intimation 

 that he was any less of geologist than before. 



Fifteen quarto volumes, comprising 4,539 pages and L,081 full page 

 plates of fossils, stand as an enduring monument to his industry, u 

 record which never has, and presumably never will be, surpassed in 

 the annals of American geology." 



In 1841 Hall, fresh from his work on the geological survey of New 

 York, made a tour through the then western State of Ohio to the 

 Mississippi River, with a view of furthering the work of Vanuxeni in 

 1829 relative to the identity of certain of the western 

 Hairs work in Ohio, formations with those of New York. As a result, he 

 claimed that the rocks seen near Cleveland were "per- 

 fectly identical with those of tin 1 middle portion of the Portage group," 

 and that the rocks of tin' Chemung group, now known to be Waverly, 

 appeared near Newbury and Akron. The Clin 1 ' limestone of the Ohio 

 geologists he regarded as the equivalent of the Helderberg series of 

 New York, or at least of the Onondaga and Corniferous members/' 

 Perhaps the most important of his generalizations was the following: 



From the facts here stated, the conclusion seems unavoidable that the character 

 of fossils is, or may he, as variable as lithological characters; in fact, that the species 

 depend in some degree upon the nature of the material among which they lived. 

 fossil characters, therefore, become of parallel importance to the lithological; and, 

 in order- to arrive at just conclusions, both must be studied in connection, and local- 

 ities of proximity examined. In the case of the Hudson River group of shales and 

 sandstones, in passing from New York to Ohio the lithological character is almost 

 entirely changed, and at the same time also the most prominent and abundant 

 fossils are unlike those of the group in New York. More careful examination, how- 

 ever, reveals the fossils which characterize this group at the East, and also at the 

 same time some obscurely similar lithological characters. Similar lithological changes, 

 accompanied by like changes in fossils, occur in more limited districts within the 

 State of New York. Without desiring to diminish the value of fossil characters as 

 means of identifying strata, it must still be acknowledged that similar conditions in 

 the lied of the ocean, and, apparently, similar depth of water, are required to give 

 existence or continuation to a uniform fauna; and when we pass beyond the points 

 where these conditions existed in the ancient ocean, we lose, in the same degree, the 

 evidences of identity through successive depositions, often of very different nature; 

 yet, at the same time, these may not have had a very wide geographical range. 



" Prof. Charles Schuchert informs me that if to the above are added his miscella- 

 neous publications in octavo the number of pages of text published during his life 

 may safely lie set down as not less than 10,000. Large as are those figures, they 

 were, however, exceeded by the celebrated Bohemian paleontologist Barrande, who 

 issued during his life is quarto volumes, comprising 5,568 pages of text and 798 

 plates of fossils, besides leaving manuscript and material for at least 10 volumes 

 more, of which 4 have been issued since his death. 



& At that time, the Corniferous, Schoharie, Cauda-galli, Oriskany, and the 

 Onondaga, or Salina and Waterlime, were considered subdivisions of the Upper and 

 Lower Helderberg. 



