250 THE CAMBRIAN. [bull. 81. 



that excerpts from volume 1 of the Geology of Vermont were distributed 

 prior to December, 1861, and that it was in print by July, 1861. £ 



On a map, in the atlas accompanying the Geology of Canada for 1863, 

 published in 1865, the Georgia group of Prof. Hitchcock is included 

 with the " Red Sandrock n in a common color, and is so referred to in 

 the legend. This includes the u lied Sandrock" series and the Geor- 

 gia series of Prof. C. H. Hitchcock as one formation under the name 

 of Potsdam. 



In 1886 the " Red Sandrock " was included by Mr. C. D. Walcott 

 with the shales of the Georgia series, in the Middle Cambrian or Geor- 

 gia group. 2 The reference to the Middle Cambrian was changed to 

 Lower Cambrian three years later. 3 



GRANULAR QUARTZ. 



This is one of the first formations differentiated and named by Prof. 

 Amos Eaton. 4 He referred it to the Primitive class and indicated its 

 stratigraphic position on a section accompanying the index. The name 

 was accepted by Dr. E. Emmons 5 in 1842 and placed as the second 

 member of his Taconic system, between the second bed of Stockbridge 

 limestone and the third bed of limestone. This section was corrected 

 in 1814, so as to place the "Granular Quartz" at the base of the Taconic 

 system. 6 



In 1887 the Olenellus fauna was discovered by Mr. C. D. Walcott in 

 the "Granular Quartz" near Bennington, Vermont, thus determining 

 its pre-Potsdam age. 7 



RED SANDROCK. 



The occurrence of a red sandstone at Burlington Falls, Vermont, was 

 mentioned by Prof. C. T. Jackson in 1844. 8 



In the scheme of Dr. C. B. Adams, illustrating the rocks of Vermont, 

 as expressed in the nomenclature of the New York system, the Red 

 Sandrock occurs above the Hudson River shales. 9 



The correlation thus indicated is that of the reddish brown Medina 

 sandstone of the New York series with the reddish colored "sandstone" 

 of Vermont, and the name Red Sandrock was applied to the latter, 

 thus originating a term that has continued in geologic literature, not- 



1 Date of the publication of the report upon the Geology of Vermont. Boston Soc. Nat. Hist. Proc., 

 vol. 24, 1888, p. 34. 



2 U. S. Geol. Survey, Bull. No. 30, 1886, p. 44. 



8 Stratigraphic position of the Olenellus Fauna in North America and Europe. Am. Jour. Sci., 3d 

 ser., vol. 37, 1889, p. 383. 



4 An index to the Geology of the Northern States, with a transverse section from Catskill Mountain 

 to the Atlantic. Leicester, 1818, p. 21. 



6 Geol. of N. Y., Tart 2, comprising the survey of the 2d Geol. (Northern) District, 1842, p. 144. 



6 The Taconic System ; based on observations in New York, Massachusetts, Vermont and Rhode Isl- 

 and. Albany, 1844, p. 18. 



7 Discovery of fossils in the Lower Taconic of Emmons. Am. Assoc. Proc, vol. 3G, 1888, p. 212. 



8 Final report on the Geology and Mineralogy of the State of New Hampshire, 1844, p. 161. 



9 First Ann. Rep. on the Geology of Vermont. Burlington, 1845, p. 61. 



