974 THE JOURNAL OF GEOLOGY. 
limestones of the Great Valley to the Pocono sandstones of Lower 
Carboniferous age. ‘There are also some small dikes of diabase in the 
northwestern corner of the area. The region is one in which relatively 
gentle folds predominate. There is an overthrust fault which extends 
along the western side of the Great Valley for some distance, and 
several other faults traverse the Shenandoah limestone. 
The geologic classification does not differ materially from that 
outlined by W. B. Rogers, but geographic names have been applied to 
the formations. The name Shenandoah limestone has been selected 
for the great series of limestones of the valley. This series comprises 
several subdivisions, but they merge so gradually in the Staunton region 
that no attempt has been made to differentiate them on the map. The 
upper member contains a Trenton fauna, and it is thought that the 
basal beds of the series extends into the Cambrian, although no fossils 
have been discovered in them. Next, there is the representantive of 
the Utica and Hudson shales, which has been designated the Martins- 
burg shale. It is overlain by the Massanutten sandstones, which 
comprise the Oneida and Medina, in terms of the New York series. 
Next, there are the Rockwood formation and the Lewistown limestone, 
which include the formations between the Clinton and Lower Hel- 
derberg. The Oriskany and associated sediments are here represented 
by a stratigraphic unit to which thename Monterey sandstone has been 
given. The great series of Devonian strata lying above the Monterey 
has been divided into the Romney shale, Jennings formation, and Hamp- 
shire formation. As they are not sharply separated from each other 
the patterns by which they are represented on the map are merged 
over a narrow zone along their boundaries. Only a portion of the 
Pocono formation is included in the stratigraphic column in the region. 
The principal economic resources are iron ores, which lie on a local 
unconformity between the Monterey sandstone and the Romney shale, 
and limestone for flux. Some of the limestones are suitable for marbles, 
and at many points lime is burned for local use. There are several 
thin, irregular beds of coal in the Pocono sandstone, but they are not 
of economic importance. Brick and pottery clays in the Great Valley 
complete the list of economic resources. 
U.S. Geologic Atlas, Folio 15, Lassen Peak, California, 1895. 
This folio consists of two pages of text by J. S. Diller, geologist, 
descriptive of the Lassen Peak district, supplemented by two pages, 
with illustrations (nine figures), devoted to recent volcanic activity; a 
