144 THE CAMBRIAN. Iblu.81. 



tion of two or three small patches not over 10 miles in diameter. 1 A 

 description of sections from Athens and Knoxville, Tennessee, to Mur- 

 phy, North Carolina, accompany the paper. 



Tbe descriptive notes and conclusions of Prof. Bradley were followed, 

 in 1883, by the expression of a somewhat similar view of the age of the 

 Southern Appalachians by Mr. J. B. Elliott, 2 in which he concluded with 

 Bradley tbat the metamorphosed strata east of the unaltered Ocoee and 

 other " Lower Silurian" rocks were formed of metamorphosed strata of 

 the Knox section. 



In the table of formations accompanying Macfarlane's American 

 Geological Railway Guide, Prof. J. M. Safford arranges the formations 

 now referred to the Cambrian in the following descending order : 

 3b. Knox shale. 

 3a. Knox sandstone. 

 26. Chilhowee sandstone. 

 2a. Ocoee group. 



He places as equivalent formations, following Dana's Manual, the 

 Ocoee and the Acadian ; the Chilhowee and the Potsdam; the Knox 

 sandstone and the Calciferous; and the Knox shale and the Quebec. 

 This is the classification suggested by Bradley. 3 The Metamorphic 

 group, liTo. 1, beneath the Ocoee group, is correlated with the Archean. 



In an attempt to assign to the proper stratigraphic horizon the rocks 

 referred to the Cambrian group in the United States and Canada, Mr. 

 C. D. Walcott correlated the Knox shale and sandstone with the Pots- 

 dam sandstone. The supposed subjacent Chilhowee sandstone and 

 Ocoee conglomerate were referred to a position corresponding to the 

 horizons of the Olenellus and Paradoxides faunas. 4 Subsequently, 

 references to the two formations were omitted, pending an investiga- x 

 tion of their true stratigraphic position. The discovery, in 1889, of the 

 Olenellus fauna in the shales resting conformably in the Chilhowee 

 series, thus verifying Prof. Safford's section, affirms the correlations 

 of 1883, except that it carries the Middle Cambrian zone above the 

 Chilhowee sandstone and drops the Ocoee, if it proves to be beneath 

 the Chilhowee quartzite, back into the Basal Cambrian. 



GEORGIA. 



Of the Transition, or older fossiliferous rock formation, Mr. George 

 White said, in 1849, that it has been less explored than any other part 

 of the geology of Georgia. 



That part of it which extends from the western base of the primary rocks to the 

 Chattoogatta range of mountains, and which forms the valley of the Oostanaula 



1 On the Silurian age of the Southern Appalachians. Am. Jour. Sci., 3d ser., vol. 9, 1875, pp. 279, 280. 



2 The age of the Southern Appalachians. Am. Jour. Sci., 3d ser., vol. 25, 1883, pp. 282-298. 



3 Tennessee. (Geological formations.) Macfarlane's Am. Geol. R. R. Guide, 1879, p. 196. 



4 Tln< Cambrian System in the United States and Canada. "Washington Phil. Soc, Bull., vol. 6, 1883, 

 p. 100. Second contribution to the studies of the Cambrian faunas of North America. U. S. Geol. Sur- 

 vey, Bull. No. 30 1886, p. 63. 



