STRATIGRAPHICAL GEOLOGY. 44! 



B. Cambrian and Silurian System. Almost contemporane- 

 ously with Sedgwick's and Murchison's famous researches in 

 European areas, North American geologists were extending the 

 knowledge of the vast tracts of older Palaeozoic rocks in North 

 America. 



Between 1818 and 1832, A. Eaton published a series of 

 pamphlets wherein he erroneously compared the sedimentary 

 deposits in the east of the United States with the Mesozoic 

 formations in Europe. Vanuxem in 1829 proved that the 

 deposits in the east of the United States belonged exclusively 

 to the "Transitional" series. In the following decade 

 geological survey departments were established in several of 

 the eastern and southern states, after the model of the British 

 Geological Survey, and this gave a strong impulse to the 

 development of Geology and Palaeontology in North America. 

 In New York State, the official surveys were commenced in the 

 year 1836, and the survey department was divided into four 

 independent sections. The South-Western Section was placed 

 under the direction of Lieutenant Mather, the North-Eastern 

 under Professor Ebenezer Emmons, the Middle Section under 

 Conrad, and the Western Section under Vanuxem, who had been 

 trained in Paris. In 1837 Conrad retired from active field-work 

 on account of his health, and devoted himself to palaeontologi- 

 cal work. Vanuxem replaced him as director of the Middle 

 Section, and J. Hall was given the Western Section. 



Emmons, in 1842, published the general results obtained in 

 the North-Eastern district, which in a large measure is com- 

 posed of crystalline plutonic masses, gneiss, and crystalline 

 schists. Among the sedimentary deposits, the " transitional " 

 series has the widest extension. Emmons applied local names 

 to the several divisions, calling the main complex of Palasozoic 

 rock the " New York System," and sub-dividing it into four 

 members irrespective of European classificatory groups i, 

 Champlain; 2, Ontario; 3, Helderberg; and 4., Erie Group. 

 According to Emmons, the New York system was succeeded 

 by the Old Red system, and rested upon the Taconic system. 

 The latter reposed on the crystalline schists, and was said 

 to consist of an unfossiliferous complex of slates, flagstones, 

 limestone, and quartzite attaining a thickness of about 25,000 

 feet. The unfossiliferous complex was strongly contorted and 

 disturbed, whereas the deposits of the New York system were 

 almost horizontal. 



