790 



SCIENCE. 



[N. S. Vol. II. No. 50. 



ago, but no fossils have been found in the 

 area of the Fredericksburg sheet. 



FOLIO 14, STAUNTON, VIRGINIA-WEST VIRGINIA, 

 1894. 



This folio consists of 4 pages of text, signed 

 by N. H. Darton, geologist, and closing with 

 a columnar section of the area ; a topo- 

 graphic map (scale 1:125,000), a sheet show- 

 ing the areal geology of the district, another 

 showing the economic geology and a third 

 exhibiting structure sections. 



The area represented is about 1,000 

 square miles of central Appalachian Vir- 

 ginia. It comprises central and western 

 Augusta county and portions of several ad- 

 jacent counties. Staunton lies near the 

 center of the eastern margin of the tract. 

 About a third of the area is in the Great 

 Valley of Vii'ginia, and tiie remainder 

 stretches halfway across to the Alleghany 

 Mountains. 



The geologic formations comprise mem- 

 bers ft'om the Shenandoah limestone of the 

 Great Valley to the Pocono sandstone of 

 Lower Carboniferous age. There are also 

 some small dikes of diabase in the north- 

 western corner of the area. The region is 

 one in which relatively gentle folds pre- 

 dominate. There is an overthurst fault 

 which extends along the western side of 

 the Great Valley for some distance, and 

 several other faults traverse the Shenan- 

 doah limestone. 



The geological classification does not dif- 

 fer materially from that outlined by W. B. 

 Rogers, but geographic names have been 

 applied to the formations. The name Shen- 

 andoah limestone has been selected for the 

 great series of limestones of the valley. 

 This series comprises several subdivisions, 

 but in the Staunton region they merge so 

 gradually that no attempt has been made 

 to differentiate them on the map. The up- 

 per member contains a Trenton fauna, and 

 it is thought that the basal beds of the se- 



ries extends into the Cambrian, although no 

 fossils have been discovered in them. Next, 

 there is the representative of the Utica and 

 Hudson shales, which has been designated 

 the Martinsburg shale. It is overlain by 

 the Massanutten sandstones, which comprise 

 the Oneida and Medina in terms of the 

 New Yoi'k series. Next, there are the 

 Eockwood formation and the Lewistown 

 limestone, which include the formations be- 

 tween the Clinton and Lower Helderberg. 

 The Oriskany and associated sediments are 

 here represented by a stratigraphic unit to 

 which the name Monterey sandstone has 

 been given. The great series of Devonian 

 strata lying above the Monterey has been 

 divided into the Eomney shale, Jennings 

 formation and Hampshu-e formation. As 

 they are not sharply separated from each 

 other the patterns by which they are repre- 

 sented on the map are merged over a nar- 

 row zone along their boundaries. Only a 

 portion of the Pocono formation is included 

 in the stratigraphic column in this region. 



The principal economic resources are iron 

 ores, which lie on a local unconformity be- 

 tween the Monterey sandstone and the Rom- 

 ney 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. 



FOLIO 15, LASSEN PEAK, CALIFORNIA, 1895. 



This folio consists of 2 pages of text by 

 J. S. Diller, geologist, descriptive of the 

 Lassen Peak district, supplemented by two 

 pages, with illustrations (9 figures) , devoted 

 to recent volcanic activity; a topographic 

 map of the district, a sheet showing the 

 areal geologj' and another showing the 

 economic geology. 



The Lassen Peak district is situated in 



