442 HISTORY OF GEOLOGY AND PALAEONTOLOGY. 



The report of Varmxem, published in the same year (1842), 

 took the same general standpoint as that of Emmons, but 

 Vanuxem extended the name of New York system so as to 

 include the Old Red Sandstone. Mather (1843) in his official 

 report protested against the independence of the Taconic 

 system, contending that it was a strongly metamorphosed 

 representative of the Champlain group. In this view, Mather 

 was supported by Hitchcock, Rogers, Dana, and J. Hall. 1 

 The report by Hall (1843) gave an admirable exposition 

 of the three upper divisions of the New York system. The 

 subordinate groups proposed by Vanuxem and Conrad were 

 for the most part accepted, and a few additional groups 

 were introduced, so that the New York system (exclusive 

 of the Old Red) was now sub-divided into twenty-nine 

 groups. 



Hall made a comparison between the palasontological 

 sequence in these groups and the sequence that had been 

 worked out by Murchison and Sedgwick. For the five lower 

 groups (from the Potsdam sandstone to the Trenton limestone) 

 Hall could adduce no British equivalent ; the Utica slates 

 were compared with the Llandeilo slates (Lower Silurian) of 

 Murchison ; the groups from the Hudson river beds and the 

 Clinton group were said to be equivalent with the Caradoc or 

 Bala shales and flagstones; the groups from the Niagara beds 

 to the Corniferous-Limestone group were compared with the 

 Wenlock shales and limestones ; and the strata from the Mar- 

 cellus and Hamilton groups to the Chemung group were 

 regarded as the equivalent both of the uppermost or Ludlow 

 division of the Silurian system and of the Devonian system. 

 Each of Hall's groups is very accurately characterised accord- 

 ing to stratigraphical, lithological, and palaeontological features. 

 And as the strata in the area examined by Vanuxem and Hall 

 follow almost everywhere in horizontal or gently inclined 

 position without any appreciable tectonic disturbances, the 

 sub-divisions erected by these geologists have undergone little 

 subsequent modification. Some time later, Hall described 

 in a series of handsomely-illustrated volumes the Palaeozoic 



1 James Hall, born on the I2th September 1811, at Hingham in Massa- 

 chusetts, received his scientific education at the Polytechnic School of 

 Troy; in 1836, entered the Geological Survey Department of New York 

 State, and was afterwards Director of the Natural History Museum in 

 Albany. He died in his eighty-seventh year (1898) in Albany. 



