96 THE CAMBRIAN. (bull.81. 



" Quartz Rock n in the final report of tbe Geological Survey of Vermont 

 by Prof. C. H. Hitchcock. 1 Detailed descriptions are given of its char- 

 actor as found in Vermont, where it is said to have a thickness of at least 

 1,000 feet. 2 On this same page we read that u much of the quartz rock 

 in the valley between Bristol and Starksboro can not be distinguished 

 from members of the red sandrock series." Several species of fossils 

 are mentioned as occurring in it; they are : A species of Lingula, a mol- 

 lusk, resembling the Modiolopsis, a straight chambered shell (?), a few 

 crinoidal columns, the Scolithus linearis (Hall), a few fucoids, and some 

 indeterminable forms which are evidently organic. 3 The exact geolog- 

 ical horizon of the quartz rock is not determined. 



At this point the review of the literature referring to the " Granular 

 Quartz " will be postponed until it is taken up in connection with the 

 " Red Sandrock" and u Georgia Slates" of Vermont. In 1861 the three 

 formations were practically united in one geologic terrane by the dis- 

 coveries of Messrs. Billings and Barrande and the correlations of the 

 Geological Survey of Vermont. A review of the references made to 

 the Red Sandrock and the Georgia Slates will next be given, and 

 then the three formations will be considered together as they are de- 

 scribed in New York and Vermont. 



RED SANDROCK. 



When describing the formation terminating the Champlain group of 

 the New York section Dr. E. Emmony correlated tbe brown or red- 

 brown sandstone of Vermont, on the eastern border of Lake Cham- 

 plain, as found at Addison, Charlotte, Burlington, and Colchester, with 

 the gray sandstones that terminate the Lorraine shales of Jefferson 

 County, New York. 4 He thus assigned the "Red Sandrock" of the 

 future to the summit of the Lower Silurian. 



In presenting the results of his study of a section crossing Vermont 

 from the Green Mountains to Lake Champlain, Prof. C. T. Jackson 5 

 mentions the occurrence at Burlington Falls of a red sandstone con- 

 taining numerous beds of buff colored and blue compact limestone des- 

 titute of fossils. He referred it to tlie Potsdam sandstone of Dr. Em- 

 mons. "At Willard's quarry the red sandstone rock alternates with a 

 bright red slate, covered with ripple marks made by the waters, from 

 which the sediment was originally deposited." He further states that 

 a mile from Burlington, on the Winooski River, large beds of compact 

 blue and excellent white limestone are found. 



Prof. C. B. Adams describes in the first report of the Geological 



* — 



1 Hypozoic and Paleozoic rocks. Report on the Geology of Vermont, descriptive, theoretical, econom- 

 cal, and scenographical, vol. 1, 1861, pp. 342-357. 



3 Op. cit., p. 355. 

 *Op. cit., p. 356. 



4 Geology of New York, pt. 2, comprising the~ survey of the second geological (northern) district. 

 1842, pp. 123, 124. 



e Final Report on the Geology and Mineralogy of the State of New Hampshire, with contrihutions 

 towards the improvement of agriculture and metallurgy. Concord, 1844, p. 161. 



