16 TJie Anici'ican G^'ologl^t. July, inns 
The beds undoubtedly comprise not only the Oriskany , but in their 
upper portion the representatives of the several coordinate members 
of the (^orniferous group. For this reason and the general uncer- 
tainty of precise correlation a new name has been adopted for the 
formation. This name is that of the county seat of Highland count)'. 
Virginia, a region in which the formation is extensively developed. 
Whether to class the Monterey sandstone in the Devonian or Silurian 
is a question which will have to be decided by the paleontologists. 
Between the Monterey sandstone and the slates of the next 
succeeding formation there is an unconformity by erosion which 
presents some interesting features. Its vertical extent is not 
great, and it is apparently confined to the more eastern series of 
exposures, but it appears to extend for some distance along the 
Appalachians. In the region west of Staunton the Montere}- 
sandstone beds are eroded to a varying depth which reaches its 
maximum in an area northeast of Goshen, where the black slates 
of the Devonian lie on an irregular eroded surface of the cherty 
member of the Lewistown limestone, the Montere}' sandstone 
having been entirely removed. The southern extension of the un- 
conformity has not been studied with care, but the abrupt break 
b(;tween the black slates and Monterey sandstone is frequently ob- 
served for many miles southward. The absence of the Monterey 
sandstone and Lewistown limestone in the New River region is 
probably due to this unconformity', the occasional masses of black 
chert occurring in their place being the remains of the detritus of 
the latter. In Pennsylvania similar relations have been described 
in some of the central counties, where the "Oriskany" and more 
or less of the associated formations have been locally removed. 
In central Virginia and also in Pennsylvania to a less extent 
there are iron ore deposits at the base of the Devonian shales. 
In Virginia these deposits have been extensively worked at Low 
Moor, Longdale, Victoria Mines, Ferrol, Pond Gap, and many 
other places, and their existence appears to be closeh' related to 
the unconformity. 1 have examined these deposits at several 
typical localities, and they appear to lie on the eroded surface, 
where they were probably deposited as bog ores in shallow basins 
of greater or less extent. They have since been buried under 
the great mass of Devonian and Carboniferous deposits, and more 
or less secondary arrangement has taken place. This secondary 
deposition would be necessary, perhaps, to account for the nature 
