November 13, 1896.] 



SCIENCE. 



703 



the paleontology of New York. While 

 Babbage, Hopkins, Herschel and other 

 Britons previously discussed the mobility 

 of the earth- crust, and while Powell later 

 made the correlative discovery that moun- 

 tainous areas rise with unloading and But- 

 ton still later formulated the doctrine, this 

 publication by Hall was one of the most 

 important contributions ever made to the 

 doctrine of isostasy. 



One of the early publications of the New 

 York Survey was a preliminary geologic 

 map of the State. Portions of this map 

 (particularly the western portion, or Fourth 

 District) may be characterized as accurate 

 to scale, and up to the geographic knowledge 

 and cartographic methods of the times ; 

 other portions (particularly the complex 

 districts of the east and north) were far 

 from satisfactory. When Hall assumed 

 charge of the entire geologic and paleonto- 

 logic work of the State he planned to revise 

 the early cartographic work and to issue a 

 map comparable with the splendid qnarto 

 volumes in accuracy and dignity. Many 

 obstacles stood in his way; the State was 

 practically unsurveyed, so that there was no 

 trustworthy basis for the geologic mapping; 

 the structure, especially in the eastern and 

 northern districts, was intricate and ob- 

 scure ; extensive areas were so deeply cov- 

 ered by Pleistocene deposits as to conceal 

 the substructure which he desired to repre- 

 sent ; the means at disposal were limited ; 

 and from time to time official obstacles, 

 which need not be stated in detail, arose to 

 prevent the execution of his plan. So the 

 months grew into years and the years 

 rolled into decades, and his ambition re- 

 mained unfulfilled. About ten j^errs ago a 

 number of detailed surveys were brought 

 to completion, an urgent demand for a ge- 

 ologic map of the Empire State had arisen, 

 and the plan seemed about to mature. At 

 this stage Prof. Hall sought the cooperation 

 of Major Powell, tlien Director of the Fed- 



eral Survey, and a cooperative plan was 

 adopted, under which it fell to me to aid 

 in the work. Unhappily the difficulties 

 in the way of mapping the formations of 

 the State were by no means overcome, and 

 once more the months grew into years, 

 which rolled into another decade before the 

 ambition of the veteran officer was even 

 partially gratified. First it was found 

 necessary to examine and reduce the records 

 accumulated during fifty years ; then field 

 studies in type localities were required in 

 order that the records might be interpreted; 

 next it was found that the base maps were 

 wholly inadequate. So the geologic map- 

 ping was suspended and a base map was 

 compiled from the best available sources ; 

 then the geology was revised and duly 

 transferred; with every operation the stand- 

 ard of accurac}'^ and general excellence rose, 

 and it was found that in many districts 

 geologic knowledge was insufficient to war- 

 rant mapping on the scale adopted. Thus 

 fresh surveys were required ; and many 

 days were spent in company with Prof. 

 Hall in reconnoissances and surveys in the 

 Mohawk Valley and about the southern 

 flanks of the Adirondacks, and I can never 

 forget the vigor and determination with 

 which the octogenarian geologist pushed 

 over the rugged hillsides, sometimes plow- 

 ing through snow and wading through 

 floods, in the hope of raveling complex 

 relations among the rocks. Many others 

 were enlisted in the work. Kemp, Merrill, 

 Smythe, Clarke and Beecher, and, espe- 

 cially toward the last, Darton, made im- 

 portant contributions ; with the aid of 

 these and other collaborators the map was 

 finally brought to such state of completion 

 as to warrant issue. A small proof edition 

 of the map was printed early in 1896, 

 through the courtesy of Hon. Charles D. 

 Walcott, Director of the Geological Survey. 

 No one can be more painfully aware than 

 the compiler of the many imperfections of 



