WILLIAMS AN 
KINDLE. 
D ] CONTRIBUTIONS TO DEVONIAN PALEONTOLOGY. 45 
cases the faunal evidence suggests this interpretation. More evidence 
will be required before safe generalizations can be drawn as to the 
sequence of faunas in this part of the area. 
CORRELATIONS. 
By H. S. Williams. 
The limestone and the terminal Silurian sandstone of the Estill ville 
folio are undoubtedly the constituent parts of the t4 Hancock lime- 
stone " of that folio. The Hancock limestone is described as thinning 
out to the southeast, and in the correlation given by Campbell, it is 
the equivalent of the Meniscus limestone of Safford and of the Oris- 
kany and Lower Helderberg of Stevenson. a 
The Giles formation of the Pocohontas quadrangle is correlated with 
the Lower Helderberg and Oriskany by Mr. Campbell. 6 In north- 
ern and central Virginia the Lewistown limestone, including the chert 
lentil, is correlated with the Lower Helderberg, Salina, and Niagara, 
and the Monterey sandstone is correlated with the Oriskany. c 
Mr. Darton describes the underground erosion of the Lewistown 
limestone as follows: 
The limestones are cavernous and many extensive caves have been discovered. 
One of them, the Blowing Cave, is in a small anticline traversed by Cowpasture 
River, 6 miles west of Panther Gap. * * * Springs, sinks, and other evidences of 
underground drainage are of general occurrence in the limestone area. 
In this region the thickness of the Lewistown limestone varies from 
550 to 1,080 feet, and that of the Monterey sandstone from 50 to 200 
feet. 
It will be noticed also that the black shale caps the series in all the 
sections described in all this part of the Appalachian province. 
In Maryland the lower member is called Helderberg and varies from 
750 to 900 feet in thickness, followed by black chert lentils. The 
next formation is the Oriskany, 325 to 350 feet thick, which is capped 
by the black shales of the Romney formation. ^ 
These definitions are consistent with the following generalization: 
Upon a more or less pure limestone terrane of varying thickness (the 
Hancock, Lewistown, Helderberg) was deposited a cherty limestone 
which becomes sandy and ends in coarse sandstone, occasionally 
described as conglomerate; above these are the cherty lentils of the 
limestone (Giles formation or Monterey sandstone); above these is the 
base of the extensive Devonian black shale (Chattanooga, Romney). 
In most cases there is more or less distinct evidence of underground 
solution of the limestone underlying the black shale. From a forma- 
aGeol. Atlas U. S., folio 12. 
b Campbell, Geol. Atlas U. S.. folio 26. 
e Carton, Geol. Atlas U. S., folio 61. 
d Clark, W. B., Maryland Geol. Survey, Allegany County, 1900. 
Bull. 244—05 4 
