ORISKANY OF VIRGINIA 317 



always covered by the " Black shale " of Safford or its equivalent in this 

 region — the Hamilton formation of Stevenson. The latter describes the 

 Oriskany as follows : 



" This is a sandstone, probably not more than 35 or 40 feet thick, which is shown 

 in the Poor valley of Powell river [Lee and Scott counties, near the Tennessee state 

 line] and along the valleys of Wildcat creek and the North fork of Clinch ; also 

 along the latter stream at the foot of Powell mountain, and in the Hunter valley 

 at Stony creek. ... 



"The Oriskany sandstone is coarse, reddish on exposed surface, but white on 

 the fresh surface. It is friable, and at some localities, notably along the North 

 fork of Clinch river, it readily disintegrates on exposure. . . . This rock con- 

 tains Hipparionyx proximus in Stony creek; in the Poor valley of Powell river, it 

 contains Merislella lata, but with that there occur some forms [Spirifer perlamel- 

 losus]* belonging to the Helderbergian. 



" The Oriskany was seen only in Bland county, where it is exposed at the foot 

 of Round mountain and the Garden mountains, as well as along the foot of Wolf 

 Creek mountain in the ' Wilderness.' The rock is a thin sandstone, which resists 

 the weather so well as to make a small ridge. ... As shown in the ' Wilder- 

 ness,' the rock is a moderately coarse gray sandstone, evidently not more than 

 ten feet thick."! 



A Lower Oriskany horizon appears to be present on Flat Top mountain, 

 near Saltville, Smythe count} r , Virginia. Here in chert were collected 

 the following species, which the writer identified for a correspondent of 

 the United States National Museum : 



Leptoccelia, fragment. Rhynchospira, near globosa, but with three 



Meristella. central plications, on each side of which 



Spirifer hemicyclus Meek and Worthen. are two large ones. 

 CJionetes melonica Billings. Zaphrentis, like Z. rcemeri. 



Platyceras gebhardi Conrad. 



CLEAR CREEK LIMESTONE AND UPPER ORISKANY OF ILLINOIS 



In the spring of 1858 Professor A. H. Worthen identified the Oriskany 

 formation in Alexander and Union counties, Illinois, but did not de- 

 scribe it until 1866. He then restricted the Oriskany to a " quartzose 

 sandstone " horizon from 40 to 60 feet in thickness overlying his " Clear 

 Creek limestone."]; The former horizon was then regarded as the base of 

 the American Devonian, but in southern Illinois, he writes — 



i( It is underlaid by a group of silicious limestones [Clear Creek limestone], that in 

 their upper beds contain well marked Devonian fossils, and below, those that seem 

 to be characteristic Upper Silurian forms; thus forming beds of passage from the 



* Proe. Amer. Phil. Soc, January, 1881, p. 234. 



f Ibid., March, 1887, p. 84. 



% Geol. Survey of 111., vol. i, 1866, pp. 124-129. 



