﻿Geology and Mineralogy. 241 



to be correct" — a statement which, in justice to Italian and other 

 investigators, and to right scientific methods, had better have 

 been withheld, and kept in the form of a private doubt, until the 

 author of it had investigated the region ; for it is putting his 

 ignorance against others' knowledge in a case where only field- 

 study can decide as to the truth. 



The difficult question with regard to the age of metamorphic 

 rocks over the globe has had, in fact, little careful study, and 

 partly because of " settled opinions." Work however is going 

 forward by geologists who are not disposed to avoid the onus 

 probandi, and a chronological scheme probably will be finally 

 arrived at based on positive knowledge of the kinds that were 

 made in successive ages. j. d. d. 



8. Preliminary Report upon Petroleum and inflammable Gas 

 of Ohio, by E. Orton, State Geologist. 76 pp., 8vo. Colum- 

 bus, O. — Mr. Orton treats of the geology of the petroleum and 

 gas of Ohio, and also of matters of economical interest. The 

 rock yielding the large supplies of these materials in Ohio is the 

 Trenton limestone, in Wood, Hancock and Allen Counties of 

 northwestern Ohio. Borings go down a thousand feet or more 

 below the surface, but not over 50 feet into the Trenton. At 

 Findlay, in this part of Ohio, the Karg well yields 12,000,000 

 cubic feet of gas a day. Oil and gas are also obtained from the 

 Berea grit, a sandstone of the Subcarboniferous, in eastern Ohio. 

 But its largest gas-well yields only 35,000 cubic feet per day. In 

 some places the overlying sandstones of the Waverly and Coal 

 measures are sparingly productive. Some oil and gas come also 

 from wells in the Devonian shales, but the supply is small. In a 

 very moderate way gas is derived from borings into the glacial 

 drift, and the supply is sometimes sufficient for " household ser- 

 vice" and "has been so used for many years at a number of points 

 in Champaign Co., Illinois." At St. Paris, Champaign Co., Ohio, 

 a place 1237 feet above the sea-level, the drill went down 510 feet 

 through drift before reaching solid rock ; and at 400 feet passed 

 much vegetable matter, as tree trunks (red cedar) and branches and 

 black soil. Such vegetable deposits have been found at many 

 places in the drift of Ohio, and are the source of the gas the drift 

 occasionally affords. 



The Findlay gas was found by Professor C. C. Howard, of 

 Columbus, to contain marsh gas, or light carburetted hydrogen 

 92-61 p. c, olefiant gas 0-30, hydrogen 2*18, nitrogen 3*61, 

 oxygen 0*34, carbonic acid 0*50, carbonic oxide 0*26, hydro- 

 gen sulphide 0-20 = 100. 



9. A peculiar feature of the Clay-beds on the icest bank of the 

 Hudson, 3 miles north of JSfeioburgh. — These beds are described 

 by Professor Wm. B. D wight (Trans. Vassar Br. Inst., Pough- 

 keepsie, 1884, '85) as inverted conoidal masses of clay made by 

 the filling of large conoidal depressions in sand-beds. Three 

 conoidal masses of clay have been opened. One of the inverted 

 conoids is elliptical in cross section, 80 by 50 feet at bottom and 



