390 CAMBRIAN AND SILURIAN IN NORTH AMERICA. [XV. 



cently discussed in my address before the American Associa- 

 tion for the Advancement of Science in August, 1871. (Ante, 

 page 251.) It is, however, to be remarked that Hall, in com- 

 mon with all other American geologists, followed Henry D. 

 Rogers in opposing the views of Emmons, whose Taconic 

 system was supposed to represent either the whole or a part 

 of the Champlain division of the New York system ; which 

 division included, as is well known, all of the fossiliferous 

 rocks up to the base of the Oneida conglomerate (and also this 

 latter, according to Emmons) ; thus comprehending both the 

 first and the second palaeozoic faunas; as shown in the pre- 

 ceding table on page 386. 



Emmons, misled by stratigraphical and lithological consider- 

 ations, complicated the question in a singular manner, which 

 scarcely finds a parallel except in the history of Murchison's 

 Silurian sections. Completely inverting, as I have elsewhere 

 shown, the order of succession in his Taconic system, estimated 

 by him at 30,000 feet, he placed near the base of the lower 

 division of the system the Stockbridge or Eolian limestone, in- 

 cluding the white marbles of Vermont ; which, by their organic 

 remains, have since been by Billings found to belong to the 

 Levis formation. A large portion of the related rocks in 

 western Vermont and elsewhere, which afford a fauna now 

 known to be far more ancient than that of the Lower Taconic 

 just referred to, and as low if not lower than anything in the 

 New York system, were, by Emmons, then placed partly near 

 the summit of the Upper Taconic, and partly, not only above 

 the whole Taconic system, but above the Champlain division 

 of the New York system. Thus we find, in 1842, in his Re- 

 port on the Geology of the Northern District of New York 

 (where Emmons defined his views on the Taconic system), 

 that he placed above this latter horizon both the green sand- 

 stone of Sillery near Quebec and the Red sand-rock of western 

 Vermont (which he then regarded as the representatives of 

 the Oneida and the Medina sandstones), and described the 

 ; as made up from the ruins of Taconic rocks (pages 124, 

 282). In 1844-1846, in his Report on the Agriculture of 



