walcott.] TENNESSEE. 143 



As known to me at the present time the dolomites and limestone are 

 referred to the Lower Silurian, as the equivalent of the Calciferous and 

 Chazy zones of the New York section. This refers the Knox si i ale to 

 the Upper Cambrian. Prof. Saiiord states that it is not easy to separate 

 lithologically the Ocoee sub-group from the Chilhowee, as they often run 

 into each other. The distinction between the latter and the Knox is 

 much more apparent. 1 



The Ocoee Conglomerate. — The typical section of the Ocoee conglom- 

 erate in the gorge of the Ocoee Eiver, is described by Prof. Saiiord as 

 follows : 



The strata are well displayed. They are, in general, coarse gray conglomerates, 

 talcose, chlorite and clay slates repeatedly interstratified, all having a seini-metamor- 

 phic aspect. The slates predominate, and of these, the greenish and light bluish gray, 

 or the chloritic and talcose varieties, are the most abundant. * * * The middle 

 part of the section presents little conglomerate, but in the upper part it abounds. 



* * * The lower part of the gorge has several bands of conglomerate. 2 



The thickness of the Ocoee formation was not determined. Provis- 

 ionally it was estimated to be more than 10,000 feet (p. 186). As shown 

 on the map, the main portion of the Ocoee conglomerate occurs south of 

 JSTolichucky River. In Johnson County, in the extreme northeastern cor- 

 ner of the State, it occurs as a narrow band next to the metamorphic 

 series. South of the French Broad River, it occupies a wide belt to the 

 Georgia line. Prof. Saiiord says it is truly a mountain-making forma- 

 tion. 



The recent work of the U. S. Geological Survey has shown that the 

 Ocoee conglomerate is of Silurian age, and it is not to be included with 

 the Cambrian. 



The description of the Chilhowee sandstone, and Knox shales and 

 sandstone, will be given in the summary of the present knowledge of 

 the Cambrian rocks of Tennessee. 



A resume of the geology is given in a report upon the resources of 

 Tennessee, by Mr. J. B. Killebrew, 3 which was prepared by Prof. Saf- 

 ford. It is a brief restatement of the character of the formations as 

 described in the "Geology of Tennessee," and the geological map ac- 

 companying it is based upon that published in 1869. 



When discussing the Silurian age of the Southern Appalachians, Prof. 

 F. H. Bradley considered that the Knox group, of Safford, included the 

 Quebec group and the Calciferous ; the Chilhowee sandstone repre- 

 sented the typical Potsdam ; and the Ocoee the Lower Potsdam or Aea- 

 •dian group. He also thought that the rocks of North Carolina, south 

 and west of the Little Tennessee, together with the metamorphic area 

 -of Georgia, north of a line parallel with and 10 miles south of the Chat- 

 tahoochee (and probably that south of this line), and the entire meta- 

 morphic area of Alabama, are Silurian or newer, with the possible excep- 



» Op. cit. , p. 182. * Op. cit. , p. 184. 



■ Resources of Tennessee. Nashville, 1874, pp.26-46. 



