320 C. SCHUCHERT — LOWER HELDERBERG— ORISKANY FORMATIONS 



which, very like the chert of Camden, are seen at many points in Benton and 

 counties north and south of it. In my excursion of 1884, however, I stopped for 

 some time at Camden to study the formations. The fossils in the chert arrested 

 my attention, and reminded me of those in the flints seen at Williams' mill in 

 1855. But at Camden the chert was in comparatively great force, at least 60 feet 

 of it being exposed. At first I was inclined to consider the chert a division of the 

 Lower Helderberg, but subsequent studies of the fossils at home forced me to the 

 conviction that as a group they must be Oriskany. The fact that the formation 

 was one of chert also pointed to this. 



"Afterwards, in 1885, 1886, and 1887, I visited localities where I thought the 

 Camden might outcrop. One of these is Big Sand}' station, in Benton, on the 

 Memphis branch of the Louisville and Nashville railroad, and near the point where 

 the road crosses Big Sandy river. Here I found the chert well developed and 

 abounding in fossils. The outcrops are as extensive and as good as at Camden. 

 For several miles south of Big Sandy, the chert appears on the hillsides as loose 

 angular gravel. 



"Five miles south, on the Lower Camden road, Lower Helderberg limestones 

 are seen cropping out from beneath Camden chert, with Tertiary beds also over- 

 lapping all in unconformable contact. 



"In Henry county the Camden chert outcrops in considerable areas, west and 

 south of the Williams Mill locality. It is seen in limited thickness above the 

 Lower Helderberg in Decatur county, and in the same relation, east of the Tennessee 

 river, in Stewart county. In the latter locality, it outcrops in the bluff on the 

 Cumberland river below Cumberland city. The greatest development of it, how- 

 ever, is on the west side of the Tennessee river, in a strip of country lying in 

 Henry, Benton, and Decatur counties. 



"In 1897 I called the attention of Mr Schuchert to the Camden chert, at the 

 same time trusting he might be able to visit the Camden locality. This he did, 

 collecting a series of fossils, which he studied, kindly giving me the results. I 

 am under special obligation to him for this visit." 



CAMDEN LOWER ORISKANY FAUNA 



Iii the spring of 1897 the writer collected Lower Helderberg fossils in 

 western Tennessee, and while in Nashville, Professor Safford also directed 

 his attention to a lot of Camden chert organisms. Since no strata of 

 Oriskany age had been recorded in Tennessee, the importance of deter- 

 mining the equivalency of the Camden chert with other regions made 

 it desirable to know more of its fauna, and with that object in view, a 

 collection was made at Camden. 



The fossils of this formation are, as a rule, natural casts both of the 

 interior and exterior of the organism, and preserve in detail the finest 

 markings. This fauna is closely related to that described by Meek and 

 Worthen* from the "Clear Creek limestone" of southern Illinois, in 

 Alexander, Jackson, and Union counties. From this region are known 

 but 11 species, and 8 of these are also found in Tennessee. They are 



*(jeol. Survey of 111., vols, i, ii, aud iii. 



