702 



SCIENCE. 



[N. S, Vol. IV. No. 98. 



age and Gliemuiig are familiar terms, in con- 

 stant use among the geologic workers and 

 teachers throughout eastern United States. 

 Other systems of nomenclature have come 

 and gone; the brilliant and attractive, yet 

 essentially procrustean, system proposed 

 by the Eogers brothers for a time competed 

 with the system devised in New York ; but 

 no other system has endured the test of 

 time. Yet the trite statement that the 

 New York formations and formation-names 

 have been found so acceptable as to outlast 

 the many transformations in the growing 

 science does scant justice to the New York 

 work. The chief merit in the New York 

 method resides in the principles recognized, 

 and these principles have not only been 

 adopted in New York and neighboring 

 States,, but have extended throughout the 

 country, and indeed have shaped American 

 geology. The New York formations were 

 defined by fossil contents, as were those of 

 England and the Continent, while the na- 

 ture and genesis of deposits were given 

 greater weight than before ; and this method 

 has been followed more or less closely by 

 the geologists of the world engaged in re- 

 searches among clastic rocks. Most of the 

 New York formations were named from 

 geographic features so chosen as to indi- 

 cate type localities and to permit endless re- 

 arrangement of the duly labeled rock divi- 

 sions as research progressed and other divi- 

 sions were recognized ; and this system of 

 nomenclature, which was practically origi- 

 nal in the New York Survey as applied to 

 minor divisions in geologic column, stopped 

 not at the boundaries of the State, but has 

 spread over the country and the world, 

 and is to-day the accepted system of civil- 

 ized lands. It might be invidious to claim 

 that any one man originated the method of 

 defining, and naming formations now in 

 general use; but it is not too much to 

 say that the method was established by th6 

 New York Survey, and that it finds its best 



illustration in the classic Fourth District ; 

 here it was that American stratigraphic 

 geology was founded. 



. Of Hall's work in paleontology, paleonto- 

 logists must speak; yet the geologist may 

 well note in passing that it was in New 

 York, and especially by the veteran scien- 

 tific ofl&cer of that State, that the geologic 

 use of fossils was first and most completely 

 established for the western hemisphere. A 

 hundred inen of genius have found in fossils 

 a key to the past history of life on the 

 earth ; others, like Walcott and White and 

 Neumayr and Barrois and a score of con- 

 temporaries, have followed the method de- 

 vised by William Smith and applied by 

 James Hall, and have thereby unlocked 

 the treasure-house of earth's resources. 



It is sometimes forgotten that, though 

 Hall was ofiScially transferred to paleon- 

 tology a full half century ago, his geologic 

 work ^as continued. Without severing 

 his connection at Albany he availed himself 

 of opportunities for researches iu: other 

 parts of the country and in the neighboring 

 Dominion of Canada ; his work in Wiscon- 

 sin was especially extended, while in Iowa 

 he organized and carried to successful com- 

 pletion a State Survey which was long the 

 standard for the Mississippi Valley. Partly 

 through these researches in other regions, 

 partly through the New York work, he 

 fitted himself to deal with problems of 

 dynamic geology, and to this subject he 

 made important contributions in papers 

 and addresses and through conferences with 

 fellow students. One of the most note- 

 worthy of these contributions, first stated 

 in his presidential address before the 

 American Association for the Advancement 

 of Science in 1856, was the inference; that 

 loaded areas of the earth-crust sink at a 

 rate conditioned by the rate, of loading. 

 This noteworthy, inference was formally 

 enunciated and discussed in the introduc- 

 tion to the third volume of the reports on 



