REVIEWS 93 



they are useful for purposes of stratigraphical correlation. The Monon- 

 gahela series carries the famous "Pittsburgh" coal bed. It is from 8 

 to lo feet thick, mined from nearly 60 mines in this one district. The 

 "Sewickley" is generally about 6 feet thick; it is second only to the 

 Pittsburgh coal in economic importance. In the Allegheny series the 

 most valuable coal seams are the Upper and the Lower Kittanning. 



The Pocono series consists of alternating beds of sandstones and 

 brown shales. It has been of enormous economic importance, because 

 it contains four oil sands: the Keener, Big Injun, Squaw, and Berea. 

 Oil and gas have been produced from various sands between the Mounds- 

 ville in middle Conemaugh series down to the Bayard sand near the 

 bottom of the Catskill beds; this is a vertical range of about 1,000 feet. 



The report is accompanied by a set of three maps, to make plain 

 the topography, the soils, and the economic geology of the district. The 

 structure contours on the geological map are of especial value and signifi- 

 cance in relation to the deposits of coal, gas, and oil. 



Cabell, Wayne, and Lincoln counties are in the extreme western part 

 of the state. Their topography is very rough, typically mature. The 

 geological formations dip in a general northerly direction, but they have 

 been somewhat warped by minor folding. The following formations 

 outcrop in these counties, in the order of their appearance, starting from 

 the north: the Dunkard, Monongahela, Conemaugh, Allegheny, and 

 the Kanawha. The removal by erosion of the Monongahela from most 

 of this area, and the irregularity and distribution of the Pittsburgh seam, 

 where the formation still remains, prevent this district from being a 

 great coal-producer. The coal of the Allegheny and Kanawha series is 

 not enough to put these counties very far from the smallest coal-producers 

 in the state. They produce about 100,000 tons per annum as compared 

 with about 4,500,000 tons shipped from the mines of the other three 

 counties reported upon. 



The north-central part of these counties is a large oil-producing 

 region; the report suggests that the southern part of the area will be a 

 fruitful field for the oil and gas prospector. 



For each of these counties there is a set of three maps which show 

 the agricultural soils, the topography, and the general and economic 

 geology. The maps are made on the scale of one inch to the mile; they 

 have structure contours showing the depth below the surface of the 

 economic deposits and the stratigraphical position of oil and gas accumu- 

 lations. 



T.T.Q. 



