wai.cott.] SUMMARY TENNESSEE. 299 



The base of the series was not observed by Prof. Stevenson, but he 

 thinks that the sandstone of Draper Mountain is not less than 2,000 

 feet in thickness. The only fossils observed were Scolithus linearis, on 

 Lick Mountain. 



In Dutchess County, New York, on the north, and in Tennessee on 

 the South, the lower portions of the limestones are of Cambrian age. 

 Whether the same is true of the arenaceous limestones above the Cam- 

 brian shales is one of the problems to be studied in Virginia. 



NORTH CAROLINA. 



The Cambrian rocks in North Carolina are the extension across the 

 border from Tennessee of the Chilhowee series with, perhaps, some of 

 the Knox shales. The best section is that along the line of the French 

 Broad from Paint Kock on the State line eastward up the river to the 

 vicinity of Warm Springs. The Paint Rock sandstone apparently is 

 the representative of the Chilhowee sandstone, and the shales the Knox 

 shales, or Upper Cambrian. The relation of the other portions of the 

 section on the French Broad to these formations is, as yet, undetermined. 



TENNESSEE. 



Ocoee conglomerate. — The descriptive details of the Cambrian rocks 

 of Tennessee are almost entirely derived from the work of Prof. J. M. 

 Safford as published in the u Geology of Tennessee" in 1869. A large 

 amount of additional data has been obtained by the geologists of the 

 U. S. Geological Survey. At my request Mr. Bailey Willis, chief of 

 Appalachian Division of Geology, prepared the following notes upon 

 the geologic position of Prof. Safford's Ocoee formation : 



The Appalachian Paleozoic area is bordered on the eastern side by a belt of elastics 

 of very great thickness, which forms conspicuous ridges between the Archeau gran- 

 ites and the calcareous Paleozoic strata. The slates, sandstones, and conglomerates 

 of this belt, characterized by lithologic similarities among themselves and distin- 

 guished by marked lithologic contrasts from other rocks, fall into a natural group. 

 Semimetamorphic, they occupy mineralogically a position between the crystallines 

 and the unaltered sediments. Resting in many localities directly on the Archean 

 and containing fragmental granitic minerals, their apparent stratigraphic position 

 is' also intermediate between the Archean and the unaltered sediments. For these 

 reasons, and in the absence of fossils, they have been placed by all the older geolo- 

 gists at the base of the stratigraphic column. Structural facts sometimes fall in with 

 this stratigraphic arrangement, and where they do not faults have been assumed to 

 account for the superposition of the supposed older on younger strata. 



In Tennessee the type localities of these elastics are Chilhowee Mountain and the 

 Ocoee gorge, and quartzites of the Chilhowee type, but not in Chilhowee Mountain, 

 have been correctly placed above slates of the Ocoee type by Safford. Your own dis- 

 covery of fossils in the upper shales of Chilhowee Mountain appears to determine the 

 age of all these sediments as Lower Cambrian or pre-Cambrian. Bat there is an as- 

 sumption which must be sustained, or the conclusion fails in its broad application. 

 That is, that the natural grouping of these strata by physical characters into a single 

 series proves them to be of one period ; this may be the result of similar conditions 

 which existed at different periods, and the natural group may include strata of widely 



