WALCOTT.J GEORGIA. 145 



River, belongs probably to the older series of the New York formations, as those por- 

 tions which have been examined contain Potsdam sandstones, Calciferous sandrock 

 and limestones of the Trenton group. Very few fossils have been found in it. 1 



This brief description is accompanied by a map, upon which the tran- 

 sition or oldest fossiliferous formations are indicated by one color, in 

 the northwestern corner of the State. 



As in the case of North Carolina and Alabama, a long interval elapsed 

 between the first geological survey and the renewal after the conclu- 

 sion of the civil war. In 1876 Mr. George Little published an account 

 of the geological formations in Georgia, to accompany Janes's Hand- 

 Book of the State. He divides the Lower Silurian into two periods. 



The hydromica schists of the copper-bearing series of the Mobile mine and Duck- 

 "town, and Ocoee conglomerates and slates along the Ocoee River on tbe Tennessee 

 line, and on the Etowah River, near Carters ville, are tbe lowest in position of the 

 rocks iu tbe State, and form a group of (2) Primordial rocks corresponding to what 

 is called the (2a) Acadian epoch in Canada. The conglomerate is made up of feld- 

 spar and a bluish quartz. The slates are hard and siliceous. This group of rocks is 

 overlaid in the Cohutta Mountains, and on Pine Log Mountain in Bartow County, 

 by a sandstone called the Chilhowee, from a mountain of that name in Tennessee, 

 corresponding to the Potsdam sandstone in New York, * * * and belongs 

 also to the (2) Primordial period and to the (2b) Potsdam epoch. This sandstoue 

 appears in the north of Haralson and Paulding counties, and in Yonah Mountain, 

 White County, andTallulah Mountain, Habersham County, being at all these places 

 altered into gneiss by metamorphism. 



The next period, called (3) Canadian, embracing the (a) Calciferous * * * of New 

 York, * * * the (&) Quebec epoch in Canada, and the (c) Chazy limestone of New 

 York, is represented by impure sandstones and cherty dolomitic limestones in the north- 

 western counties ; by a sandstone on the western slope of the Cohutta Mountains ; and 

 in the metamorphic region to the eastward and southward by calcareous schists, hydro- 

 mica schists, marble, and itacolumite of the Quebec epoch, and by calcareous schists 

 of the (a) Calciferous epoch. 2 



This arrangement follows that of Prof. Safford in Tennessee except 

 that the Knox sandstone and the Knox shales are not included. 



In a work on " The Commonwealth of Georgia," prepared under the 

 direction of J. T. Henderson 3 in 1885, there is a general description of 

 the geology of the State. The Acadian or the Ocoee and Chilhowee 

 formations and the Knox shales are all recognized. Reference to this 

 description will be made in the summary of our present knowledge of 

 the Cambrian rocks of Georgia. 



In the Tenth Census report a brief resume of the geology is given 

 with relation to the soils formed from their decomposition. In this Mr. 

 A. K. McCutchen states that the aggregate thickness of the groups, 

 estimating the Primordial at 8,000 feet, and taking the maximum thick- 

 ness of each of the higher groups, amounts to about 20,000 feet. The 

 Primordial and Calciferous are followed by rocks referred to the Quebec 



1 Statistics of the State of Georgia. Savannah, 1849, p. 22. 



2 Little, George. Geological survey of the State of Georgia. Hand-hook of the State of Georgia, 

 -•^ulogic map of State, by T. P. Janes, 1876, p. 37. 

 logy (of Georgia). The Commonwealth of Georgia. The cotuitryl; the people; the produc- 

 tions. Atlanta, 1885, pp. 73-117. 



Bull. 81 10 



