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SCIENCE. 



[Vol. YI., No 136. 



the earths' crust, — deductions by no means plain to 

 the physicist who maintains the solidity of the globe, 

 but scarcely avoidable by those who conceive of the 

 solid crust as thin. Two Americans have independ- 

 ently complemented his theory in this respect, and it 

 happened that their arguments were both submitted 

 to the association. Professor Alexander Winchell 

 presented a paper on the sources of trend and crustal 

 surplusage in mountain structure; and, to his great 

 surprise, was followed by the reading of a communi- 

 cation from Mr. William B. Taylor, on a probable 

 cause of the shrinkage of the earth's crust, in which 

 his treatment of surplusage was so closely duplicated 

 that a single abstract may serve for both. Accepting 

 the demonstration by Button and Fisher of the quan- 

 titative insufficiency of the so-called ' contractional 

 hypothesis ' of crust corrugation, and following Dar- 

 win in his conclusion that geologic time has witnessed 

 a notable shortening of the equatorial diameter, and 

 a corresponding lengthening of the polar, these 

 gentlemen find in the change of figure a ' surplusage ' 

 and consequent ' shrinkage ' of the crust. The re- 

 adjustment of the crust to the less flattened spheroid 

 involved not only a diminution of its area, but the 

 institution of a system of shearing and other strains, 

 calculated to wrinkle the surface in all parts except 

 the polar regions; and to produce, what is actually 

 observed, — a maximum effect within the zone of the 

 equatorial bulge. The remaining half of Professor 

 Winchell's paper, found in the lunar tidal influence 

 an independent reason for the prevailing meridional 

 trend of corrugations. He saw in the lagging of the 

 tide a force tending to slip the tidal crust westward; 

 and this would result, during the ages of crust forma- 

 tion, in an ingrained meridional structure, which 

 would in turn determine the trend of subsequent 

 folds consequent on surplusage. 



Three discoveries of fossils were announced in 

 what has been disputed ground at the base of the 

 geologic column. Prof. N. H. Winchell brought from 

 the pipestone-quarry of Minnesota a contorted trilo- 

 bite of the Paradoxides type, and slabs of sandstone 

 covered with round phosphatic brachiopods referred 

 provisionally to Lingula. From these he inferred the 

 pre-Potsdam and post-Huronian age of a great series 

 of rocks in Minnesota and Wisconsin, including the 

 cupriferous rocks of Lake Superior. Prof. William 

 B. Dwight reported the discovery of a unique Pots- 

 dam locality one mile north-west of Yassar college, 

 and in the Wappinger limestone belt. Among the 

 fossils are Lingula primiformis, Lingula minima, 

 Obolella, Conocephalites, and Dicellocephalus. A 

 contribution was made to the veteran Taconic ques- 

 tion by Prof. James D. Dana, who exhibited lower 

 Silurian fossils taken at Canaan, N.Y., from the 

 ' sparry limestone ' of Emmons, a member of his 

 original Taconic system as first defined by him in 

 1842. A short discussion followed, in which Professor 

 James Hall said that the existence of Silurian fossils 

 in these rocks was claimed and admitted forty years 

 ago; and Prof. N. H. Winchell argued that Emmons's 

 later use of the title Taconic, in which he applied it 

 to certain rocks in New York, now known to be pre- 



Silurian, entitle the name to a place in stratigraphic 

 nomenclature. 



Professor Edward Orton described the gas and oil 

 wells of north-western Ohio, dwelling especially on 

 their contribution to stratigraphy. The district, as at 

 present known, centres at Findlay, where the first 

 success was achieved. The borings start in the water- 

 lime and Niagara formations, quite below the Berea 

 grit, the only rock from which the geologist would have 

 ventured a year ago to predict a supply of gas. The 

 exploration was incited by superficial indications,— 

 the occurrence of gas in springs, superficial wells, etc., 

 in the vicinity of Findlay. The flow of gas ranges 

 in different wells from 100,000 to 1,200,000 cubic feet 

 per day. The petroleum, which is not afforded in 

 great amount, is black, sulphurous, and of about 35° 

 gravity, — a description applying to all oils from lime- 

 stones. The descending section, compiled from sev- 

 eral well records, includes 275' of Niagara limestone, 

 2' to 6' of Niagara shale, 30' to 40' of calcareous shale 

 (Clinton), 200' of red shale (Medina), 300' to 400' of 

 calcareous shale (recognized by its fossils as Hudson 

 River), 250' to 275' of brown shale with fossils (Utica), 

 and 500' of porous magnesian limestone identified as 

 Trenton. This bears the gas and oil. One matter 

 of note is, that the Hudson River and Utica groups 

 of New York, which in southern Ohio are called 

 ' Cincinnati ' because they cannot be separated, are 

 here individually recognized. Another is, that the 

 Cincinnati arch, as illustrated by the attitude of 

 the Trenton, lies farther west in northern Ohio than 

 has been supposed. Its trend is nearly north-south. 



The paper which commanded most attention was 

 that of Prof. Henry S. Williams. While no single 

 element of his method is novel, his work must never- 

 theless be recognized as a new departure; for none of 

 our geologists have heretofore pursued comparative 

 stratigraphy, and the comparative study of faunas, in 

 so close combination, and in such detail. As the 

 importance of the work will command for it, in the 

 pages of Science, a fuller analysis than the necessary 

 limits of this report permit, the present notice will 

 be confined to an account of its scope and method. 

 The area studied comprises the southern counties of 

 New York, the adjoining counties of Pennsylvania, 

 and northern Ohio as far as Cleveland. In this area 

 numerous sections were studied, extending from the 

 termination of the Hamilton group in the Genesee 

 shale through the upper Devonian, and terminating 

 upward with the conglomerate underlying the carbon- 

 iferous. The examination of the sections extended 

 to minute stratigraphic details ; and the fossils from 

 each stratum were kept separate, it being found that 

 in rock series, involving alternations of beds lithologi- 

 cally different, there are usually corresponding alter- 

 nations of distinct faunas. A failure to attend to this 

 principle leads to the mingling of faunas, and conse- 

 quent misconception; its recognition makes of each 

 fauna an identifiable unit, which can be traced in its 

 geographic distribution, and its successional develop- 

 ment. It appears, for example, that the fauna of the 

 black Genesee shale is repeated in every higher black 

 shale of the column ; and that, in its successive recur- 



