204 R15C0RD OF SCIENCE FOR 1886. 



shale at its lower part; a fact iiulicatiiii^' tliat the Niagara group must 

 either thin rapidly from its outcrop or increase considerably in dip.* 



46. Wrightt gives an account of a salt mine at Piffard,in western New 

 York, where a shaft has beeu sunk 1,105 feet to beds of salt which ag- 

 gregate 80 feet in thickness within 200 feet. 



Wohlmanu finds that Sherwood has overlooked the occurrence of 

 Oriskanyin Lycoming County, Pennsylvania, for he has been able to 

 trace it for some miles in an inconspicuous ridge on both sides of the 

 great anticlinal, and separating the Lower Helderberg and Marcellus, 

 which are shown to come together on the Second Geological Survey 

 map.| 



47. The Clinton grou}) of Ohio is the subject of a memoir by Foerst, 

 and while it is only ])reliminary to a more extended and detailed 

 report, it describes the fauna and many of the outcrops. The term 

 Clinton is only used provisionally, as the formation is very closely re- 

 lated to the Niagara, and has only been distinguished from the latter 

 by being richly fossiliferous and separated by a few inches of clay or 

 marl. Its fauna does not differ materially from that of the Niagara, and 

 both are limestones of similar character. The so-called Clinton is only 

 from 10 to 15 feet in thickness in western Ohio, but is somewhat greater 

 farther eastward. It is unconformable by erosion to the Cincinnati 

 group, and holds pebbles of the latter often in considerable amount.§ 



In an economic description of the coal and iron of the Southern Ap- 

 palachian, Porter || gives some account of the Clinton group in that 

 district and describes some of its stratigraphic and structural features. 



Boyd.^ in a somewhat similar paper on southwestern Virginia and 

 adjacent parts of Tennessee, describes the geology and gives some de- 

 tailed information in regard to the structure of that region. 



48. In the continuation of their review of Rogers' Geology of the 

 Virginias, the Campbells add some interesting and valuable statements 

 on the structural and stratigraphic relations in western Virginia. The 

 Niagara is stated to consist of alternating beds of conglomerates, hard 

 sandstones and shales, calcareous in greater part in its upper members, 

 and holding occasional beds of impure limestone. The occurrence of 

 the Saliua in Virginia is thought to be open to question, but if it exists 

 it is represented by calcareous shales, with occasional limestone beds 

 in Rogers', No. V. The inseparability of the Silurian and Devonian at 

 the base of the Oriskany is urged, as the rocks and fauna of the 

 Lower Helderburg graduate into those of the Oriskany, and a much 

 better line of division is found above the latter, w^here the Corniferous 



* Buffalo Soc. Nat. Hist. Bull., vol. 5, pp. 97-98. 

 t Science, vol. 8, p. 52. 



t Philadelphia Acad. Sci. Jour., vol. :37, pp. 296-297. 

 §Denisou University, Bulletin, pp. (55-120, aud plates. 

 II American Inst. Mining Eng. Trans., 1886. 

 1[ Ibid. 



