walcott.] SUMMARY — GEORGIA. 303 



horizons in the Cambrian of Tennessee — the Lower Cambrian and the 

 Upper Cambrian. Between the two there is an unknown thickness of 

 shale, in which fossils have been found sparingly, but not in sufficient 

 numbers to determine the presence of the Middle Cambrian fauna. If 

 .the definition that the base of the Cambrian is to be drawn at the lowest 

 horizon in which the Olenellus fauna is found is applied in Tennessee, 

 the Chilhowee sandstone will be referred to the Cambrian. 



GEORGIA. 



The published information relative to the Cambrian rocks of Georgia 

 is largely contained in the work of Mr. George Little. It is summed up 

 in the compilation prepared for the Department of Agriculture, under 

 the direction of Mr. Henderson, as follows : 



Acadian. — Along the western escarpment of the Cohuttas exist beds of seinimeta- 

 morphic slates, and conglomerates, apparently of very great thickness. To this form- 

 ation, in Tennessee, has been given the name of Ocoee group, from the Ocoee River, 

 along which, near the line of Tennessee and Georgia, the rocks appear to have their 

 greatest development, or at least are most prominently displayed. 



The group as yet is not known to contain fossils, but has been referred on the ground 

 of its supposed stratigraphic relations to the Acadian epoch. A sandstone of several 

 hundred feet in thickness is conspicuously displayed in steep ridges or mountains 

 skirting the western base of the Cohutta, Pine Log and Allatooua Mountains. This 

 is the Chilhowee sandstone of Tennessee, and is believed to be the equivalent of the 

 Potsdam sandstones. In Tennessee, Scolithns impressions — worm holes filled with 

 sandy rods, somewhat softer than the body of the rock — are mentioned as a common 

 characteristic of the sandstone by Prof. Safford, and indicate a probable identity in 

 age with the Potsdam sandstone of New York. These markings have not yet, so far 

 as known, been observed in this State, but the sandstones are often filled with small 

 rounded concretions, that disappear from the weathered surface, and give much the 

 appearance presented by a cross-section of the Scolithns rods in sandstone. 



This is succeeded by hard glauconitic shales and glauconitic sandstones, associated 

 with siliceous limestones, found in a broad belt of country along the Coosa River, 

 and give rise here to what is known as the Flatwoods. Some portion of the same 

 group is found in a belt of country in the eastern portions of Gordon and Bartow and 

 the southern part of Murray, and also come to the surface again for a few miles in 

 sterile ridges on the western side of Whitfield County, between Dick's Ridge and 

 Chattoogata Mountain. Trilobites are found in some of the shales and limestones, 

 and are abundant in the Flatwoods, near Livingston, in Floyd County. 



A prominent mineral characteristic is the common appearance of green sand or 

 glauconite in the shales and sandstones, and sometimes in the limestones. This green 

 sand] may be found, on close examination, in most of the shales and sandstones, 

 and is sufficiently abuudant in some to give them a decided green color. * * * 



Knox shale. — Shales and limestone of an estimated thickness of 3,500 feet. The 

 shales are more or less calcareous, and are generally of a light green shade of color, 

 below the water surface, but weather into a great variety of shades from buff to red, 

 blue, green, brown and black, but is most generally some shade of brown. These 

 shales exist in all the counties in northwest Georgia except Dade, and are found in a 

 number of long valleys, varying from half a mile to 1 or 2miles in width, constituting 

 a large part of the area of cultivated lands in this section of the State. Among 

 these are the Oothkalooga Valley of Bartow and Gordon, the Cooehnlle and Dogwood 

 Valleys of Whitfield, and the Chattooga Valley of Walker and Chattooga. 1 



5 Henderson, J. T. : Geology (of Georgia). The Commonwealth of Georgia; the country, the people, 

 the productions. Atlanta, 1885, pp. 83, 84. 



