Virginia and the Southern Appalachians. 53 



Bridge and one-fourth of a mile north of Gilmore, on the 

 James River. Crossing the James to the south side and oppo- 

 site Gilmore, in company with Mr. Willis, a search was made 

 for fossils in the strata above the Scolithus quartzite of the 

 Balcony Falls section. At a point on a small brook about 

 three-fourths of a mile from the river a calcareous sandstone 

 was found to contain the heads of a species of Olenellus, like 

 Olenelhis Thompsoni, also Hyolithes Americanus and R. com- 

 munis. 



The discovery of these two horizons indicates that the 2000 

 feet of strata beneath the ferriferous shales of the Balcony 

 Falls section are of Lower Cambrian age, and that the shales 

 not far beneath the dolomitic limestones of the Natural Bridge 

 section are also of Cambrian age. The study of the heads of 

 Ptychoparia, found in the latter section, show them to be so 

 closely related to species from the Middle Cambrian beds of 

 Tennessee that it is impossible to correlate the shales with the 

 Upper Cambrian zone. Neither is there sufficient evidence, 

 owing to the great vertical range of the species of Ptycho- 

 paria of this type, to correlate the shales with the Middle 

 Cambrian of Tennessee ; at present we can only state that they 

 are of Cambrian age, and that the Cambrian section includes 

 the strata from the base of the dolomites, to the Archaean 

 rocks at the base of the Balcony Falls section. It is not im- 

 probable that some of the lower portion of the upper massive 

 dolomites may be of Cambrian age. 



The Doe River and Nolichucky sections of northeastern 

 Tennessee were next examined. Although no fossils were 

 found in the lower quartzites and argillites, it is evident that 

 these sections may be correlated with the Balcony Falls sec- 

 tion of Virginia. In the Doe River section there is a Sco- 

 lithus sandstone that occurs two thousand, feet or more above 

 the base of the section, and the superjacent series of calcareous 

 and shaly beds are usually removed by erosion. The Noli- 

 chucky section appears to be a greater development of the 

 same series as that exposed in the Doe River gorge. 



In central Tennessee we were joined by Mr. M. R. Campbell 

 and a large collection of Cambrian fossils was made in the 

 vicinity of Rogersville, Tennessee, and many points relating 

 to the stratigraphy of the Cambrian rocks of that region were 

 determined by the finding of typical Cambrian fossils. 



West of Cleveland, in East Tennessee, the Olenellus or 

 Lower Cambrian fauna was found near the base of the Knox 

 sandstone of Safford or the Rome sandstone of Hayes. Be- 

 neath the sandstone a considerable thickness of limestone 

 occurs and subjacent to this 2000 feet or more of arenaceous 

 and argillaceous shales in which the Olenellus fauna was 



