AMERICAN GEOLOGY DECADE OF 1840-1849. 379 



distribution of the various rocks and their fossil contents. In fact, it 

 fell short of what one would be led to expect from a 

 Newark': 5 work in perusal of his earlier papers. His district, it should 

 be noted, comprised the counties of Montgomery, 

 Fulton, Otsego, Herkimer, Oneida. Lewis, Oswego, Madison, Onon- 

 daga, Cayuga, Cortland, Chenango, Broome, Tioga, and the eastern 

 half of Tompkins. 



As a matter of petrographical interest, it may be well to note that 

 the serpentine described by Yanuxem [first in his third annual report 

 (1839) and last in his final volume (1842)] as occurring near Syracuse, 

 and concerning the origin 'of which he was then somewhat in doubt, 

 was in 1844 described as an igneous rock, and as the only mass of the 

 kind in the vicinity of the Salt Spring. This fact seems to have been 

 quite overlooked by Williams in 1887, when, working with all the 

 appliances of modern petrography, he showed the rock to be an altered 

 peridotite. 



To James Hall was assigned the fourth district in the New York 

 State Survey at the close of the first season, as already noted (p. 844). 

 This comprised fifteen counties, including all that part of the State lying 

 west of the parallel of Cayuga Lake and between Lake 

 Yo"k S Work ,n New Ontario on the north and Pennsylvania on the south- 

 east. The area includes the least disturbed portions 

 of the State, those portions where the rocks lie in a beautiful consec- 

 utive series, extending from the Medina up to and including the 

 Chemung and affording means unrivaled for the unraveling of the 

 stratigraphy of the continent. It is doubtful if, at the time this dis- 

 trict was assigned to Hall, he himself realized its possibilities — cer- 

 tainly his collaborators did not. Indeed, at the time of Vanuxem's 

 transfer and Hall's promotion the region was regarded as one of little 

 promise and was willingly relinquished to the youngest and least 

 experienced of the force. 



Hall's report, appearing in 1843, comprised 683 octavo pages, with 

 19 plates, including a colored geological map of the State and the 

 United States as far west as the Mississippi River. 



Hall adopted the term New York system, as suggested by Emmons, 

 to include all the oldest fossiliferous rocks of the State, excluding the 

 Chemung and Catskill. As denned by him it would be the equivalent 

 of what was embraced in the transition of Werner. It likewise 

 included Sedgwick's Cambrian. Murchison's Silurian, and the Devonian 

 of Phillips, omitting the Old Red sandstone. 



Concerning this he w y rote: 



Nowhere is there known to exist so complete a series of the older fossiliferous 

 rocks as those embraced within the limits of the State, and for the reason that in 

 New York, where the means of investigation ate best afforded and where the whole 

 series is undisturbed, there is manifested the must complete and continuous succes- 



