of the Devonian of Western Tennessee. 74? 



maxiinuni thickness of only about 10 feet where exposed 

 along Dry Creek, a small tributary which enters the 

 Tennessee River near Walnut Grove. It thins out to 

 the northward, being locally present in the bluff at 

 Grandview, where its greatest thickness is scarcely 4 feet. 

 The only other observed outcrop is at the town spring at 

 Linden, where it is about 3 feet thick and rests discon- 

 formably on the lower part of the Birdsong formation. 

 In these three exposures it rests in turn on the Flat Gap 

 limestone, the Decaturville chert, and the basal part of 

 the Birdsong shale, showing an unconformable relation 

 indicative of a considerable break in the sequence, which 

 is in harmony with the faunal evidence. 



"Where freshly exposed, the limestone is light gray in 

 color and rather fine-grained. It is disposed in layers 

 from 18 to 20 inches thick and appears to be magnesian 

 and highly siliceous. Upon deep weathering, it forms a 

 very porous, rotten, white and buff chert with yellow 

 clay, in which fossils abound as free pseudomorphs or 

 replacements in silica. The occurrence at Linden is more 

 impure and darker in color. 



The small fauna which has been secured includes Edrio- 

 crinus sp., Striatopora sp. (large), Plethorhyncha cf. 

 barrandei, Beachia suessana, Spirifer arenosus, 8. mur- 

 cliisoni, 8. purduei, and Platyceras gebhardi. This fauna 

 is clearly related to those of the upper Oriskany of the 

 Appalachian trough and to the succeeding Harriman 

 novaculite, having no species in common with the Linden 

 or Helderbergian. The writer was first inclined to con- 

 sider the Quail as only a member of the Harriman, but 

 because of the stratigraphic relations described below 

 under the latter formation, and because of certain faunal 

 differences — though largely negative — it seems best to 

 regard it as a distinct formation. 



Harriman novaculite. — This formation is named for 

 Harriman Creek, in Decatur County. It consists of 

 so called chert or novaculite that is nearly white on 

 fresh exposure but weathers to shades of yellow and buff. 

 It is disposed in layers ranging from a few inches to over 

 a foot in thickness, and is very hard and brittle, being 

 thoroughly fractured, where weathered, into small angu- 

 lar fragments ; in this condition it so closely resembles 

 the Camden " chert" that onlv the fossils may be relied 

 upon to distinguish these two formations. Where freshly 



