' CHARACTER OP SILURIAN FORMATIONS 403 



southwestward along the western flank of the anticline. No evidence of 

 unconformity between any of the Silurian strata has been found. The 

 appearance of unconformit}^ shown by some of the sections is due to the 

 method of drawing the sections. The measurements along the vertical 

 lines bearing the names of the localities are accurate. The drawings are 

 intended to indicate variations in thickness of formations on being traced 

 through the state, and apparent variations in thickness at the individual 

 localities are again due to the method used in drawing. 



Variations in Clinton limestone. — An examination of these sections 

 shows that the Clinton thins eastward on passing up the flank of the 

 anticline. It also changes in lithological appearance. Near the houses 

 of Halum P. Weeks (figure 1, locality 1) and S. R. Wood (locality 2) 

 the Clinton is a bluish limestone, which varies from 3 to 3i feet in thick- 

 ness and contains Favosites favosus and Dalmanella eleffantula. A t Bledsoe 

 (locality 3), beneath the trestle already mentioned, it is about 51 feet 

 thick, has a whitish color, and contains the same fossils. 



At South Tunnel (locality 4) its thickness has increased to 7 feet. 

 The upper part contains much more chert than at the preceding local- 

 ities. The chert occurs chiefly in the form of thin layers, including a 

 considerable variety of fossils. Similar chert and fossils occur in the 

 upper part of the Clinton at Baker (locality 6), 19 miles southwest of 

 South Tunnel, especially in the field south of the quarries. Although 

 the discovery of any considerable fauna in this chert requires patient 

 search, a few species are sufficiently common to be readily found. The 

 localities at South Tunnel, Baker, and Goodlettsville are the most favor- 

 able for the collection of Clinton fossils so far known in Tennessee, on 

 the western flank of the anticline. At the southern end of the quarry, 

 at Baker (plate 38, figure 1), the Clinton is 12 feet thick. It is a rather 

 thin-bedded whitish limestone, containing irregular layers and nodules 

 of chert. 



At the entrance from the pike to the stone quarries, one mile west of 

 Goodlettsville (locality G) the Clinton rests upon a layer of Ordovician 

 limestone full of fragments of Isotelus. The Clinton chert is fairly 

 abundant along the hillsides, and enough fossils are found to readily 

 establish the horizon. 



At Whites Bend (plate 38, figure 2; figure 1, locality 8) the Clinton 

 has increased to 25 feet. The interbedding of the limestone with chert 

 is very marked, especially near the top of the section. Good exposures 

 occur along the pike, west of John Scott's house. The best fossils were 

 found in the gullies west of John Suell's home. 



At Newsom (locality 12) the contact between the base of the Osgood 

 bed and the top of the Clinton limestone is best exposed along the rail- 



L VIII— Bull. Geol. Soc. Am., Vol. 12, 1900 



