672 



KEPORT OF NATIONAL MUSEUM, 1904, 



of general overthrust faulting affecting the entire region. As to the 

 age of the rocks he remained conservative, but still regarded the lime- 

 stone as beyond doubt Lower Silurian, though whether Trenton, 

 Chazy, or Caleiferous remained an open question. 



•In the Journal for 1886 he referred again to the matter, questioning 

 the reliability of the lithological evidence put forth by Emmons as to 

 the identity of his Taconic rocks and those of Sedgwick's Cambrian, 

 asserting that '•' geological investigation with reference to the Cambrian 

 had not advanced so far as to make its application safe." In this paper 

 he reported also the finding in Canaan, New York, of Lower Silurian 

 fossils in Sparry limestone, this being the oldest stratum of the Taconic 

 system, as announced by Emmons in L84± These fossils were sliced 

 and studied by Professor Dwight, of Poughkeepsie, and S. W. Ford, 

 and identified as Belonging probably to the Trenton period. 



In 1886, C. D. Walcott, then paleontologist of the U. S. Geological 



Survey, took up the subject, giving a sum- 

 mary of his results, with map, in the Ameri- 

 can Journal of Science of April and May, 

 1888. Walcott began with a systematic 

 study of the slates, limestones, and quartz- 

 ites of Vermont and the adjoining counties 

 of New York, continuing his work the fol- 

 lowing season and paying particular atten- 

 tion to areas within the counties of Washing- 

 ton and Rensselaer, New York; Bennington. 

 Vermont: and Berkshire, Massachusetts, 

 since here were found the series of sections 

 described by Emmons and nearly all the 

 localities mentioned by him. 



Mr. Walcott showed to his own satisfac- 

 tion and that of most of those having any detailed knowledge of 

 the subject that the qUartzite series belong to the Middle Cam- 

 brian, the talcose slates to the Upper Cambrian, the limestones to 

 the Caleiferous," Chazy, and Trenton, and the slates and sandstones 

 to the Hudson River group. He agreed mainly with Emmons in 

 his lithological descriptions and the general dip and arrangement of 

 the strata, but disagreed with him in his identification of the geo- 

 logical age of the formations of the Lower Taconic, the strati- 

 graphic relations of his Lower and Upper Taconic, and also as to 

 the value of the stratigraphic and paleontological identifications of 

 age. He showed that the granular quartz, supposed by Emmons 

 to be unfossiliferous and to lie at the base of his Taconic system, was 

 actually fossiliferous and the equivalent of the greater portion of the 



Fig. 139.— Charles Doolittle Walcott. 



"The supposed Middle Cambrian ami a part of the Caleiferous here described were 

 subsequently relegated to the Lower Cambrian. 



