Safford and Schuchert — Camden Chert of Tennessee. 429 



Akt. XLYI. — The Camden Chert of Tennessee and its Lower 

 Orishany Fauna / by James M. Safford and Charles 

 Schuchert.* 



Part L The Camden Chert. 



By James M. Safford, State Geologist. 



In March, 1855, the writer discovered in Benton County, 

 Tennessee, at several points, excellent outcrops of Lower 

 Helderberg shales and limestones, very rich in fossils. The 

 discovery was important, since it settled the question as to the 

 presence of the Lower Helderberg, as a distinct formation, in 

 Tennessee, west of the meridian of Nashville. In subsequent 

 years, this discovery also led to a recognition of the chert now 

 referred to as Oriskany, which I have designated the Camden 

 chert for the reason that at Camden, the county-seat of Benton, 

 is seen one of its best exposures. 



One of the localities discovered in Benton County was a 

 bluff on Big Sandy River, about five miles from its mouth, at 

 a point then in Henry County, and known as the old William's 

 Mill Site. This locality is referred to in " Geology of Ten- 

 nessee," 1869. As stated on page 325 of that book, there are 

 here exposed about 50 feet of bluish limestone, mostly shaly. 

 Above this and running back on a slope from the precipitous 

 portion of the exposure, " are loose, angular, flinty masses, con- 

 taining the fossils of the rocks below, and derived from cherty 

 layers not seen." The fossils in the chert were not numerous 

 nor in good condition, but what was seen of them led, at the 

 time, to the conclusion stated. 



In 1884, I recognized the chert at Camden as a distinct for- 

 mation. I had, in passing through the country, seen this 

 horizon and had referred it without special examination to the 

 "Silicious Group" (Lowest of Subcarboniferous), outcrops of 

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

 in Benton and counties north and south of it. In my excur- 

 sion 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 

 William's Mill in 1855. But at Camden, the chert was in com- 

 paratively 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 



* Published with the permission of the Secretary of the Smithsonian Institu- 

 tion. 



