ORISKANY OF ILLINOIS AND TENNESSEE 319 



tyum problimaticum, Orthis (Rhipidomella) musculosa, Stropheodonta mag- 

 nified, Amphigenia elongata var. curta, and Dcdmanltes (Odontocephalus) sp. 

 undet. u We have concluded to place it provisionally as an upper stratum 

 of the Oriskany. 1 ' Since the Clear Creek limestone fauna is to be corre- 

 lated with that of Becraft mountain, or the Lower Oriskany, it follows 

 that the quartzose sandstone holds the horizon of the typical, or Upper, 

 Oriskany, as developed in Albany and Schoharie counties, New York. 



The following Lower Oriskany fauna of the " Clear Creek limestone " 

 of Alexander, Jackson, and Union counties, Illinois, is on the authority 

 of Meek and Worthen : 



Anoplia nucleafa Hall. Spirifer hemicyclus Meek and Worthen. 



CamaroicecJiia speciosa Hall. Megalanteris condoni (McChesney). 



.Eatonia peculiar is (Conrad). iSiropliostylus (?) cavcellatus Meek and 

 Amphigenia curta Meek and Worthen.' Worthen. 



Anoplolheca flabellites (Conrad). Plalyceras gebhardi Conrad. 



Spirifer engelmanni Meek and Worthen Platyceras (Orthonychia) tortuosum Hall. 

 (=r. S. worthenanus Schuchert). 



CAMDEN CHERT OF TENNESSEE 



There appears to be no Oriskany present in eastern Tennessee, but in 

 the western part of the state this formation is developed and is appar- 

 ently a continuation of that of southern Illinois. It is described by 

 Professor Safford* as follows : 



"In March, 1855, the writer discovered in Benton county, Tennessee, at sev- 

 eral 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 5 miles from its mouth, at a point then in Henry county, and known 

 as the old Williams mill site. This locality is referred to in ' Geology of Tennes- 

 see,' 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, 

 containing 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 foregoing conclusion. 



" In 1884 I recognized the chert at Camden as a distinct formation. 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 



*Amer. Jour. Sci., June, 1899. 



