420 THE CANADIAN NATURALIST. [Vol. 



THE GEOLOGY OF POR'T HENRY, NEW YORK/:< 



By T. Sterry Hunt, LL.D., F.R.S. 



Port Henry, in P]ssex County, is well known as a locality 

 where the highly inclined Laurcutian gneisses, with their 

 associated limestones and iron oros, rise from beneath 

 the nearly horizontal paleozoic strata of the Champ- 

 plain valley. The gneiss just above the Port Henry 

 iron-furnaces presents alternations of lighter feldspathic and 

 darker hornblendic beds with others highly quartzose, and in- 

 cludes layers of a sulphurous magnetite which are, however, 

 insignificant when comp:ired with the great deposit of this ore 

 mined at Mount Moriah, in the vicinity. Near by is seen 

 a considerable breadth of white crystalline somewhat graphitic 

 limestone, along the eastern border of which are three smaller 

 beds of two or three feet each, of the same rock, interstratified 

 with layers of crumbling gneiss. 



Haifa mile southward, near the town, a quarry is opened in 

 a more coarsely crystalline limestone, in which, as seen in 1877, 

 were enclosed irregular masses and layers of the adjacent gneiss, 

 sometimes transversely broken, but scarcely separated, and from 

 two to three inches in thickness, though sometimes much larger. 

 The limestone was marked by lighter and darker bands, contain- 

 ing more or less graphite and pyrites, and in pirts held coarsely 

 crystalline sphene and green pyroxene, in layers. We have here 

 one of those cases which led Emmons and Mather to assert the 

 eruptive character of these limestones, and it is probably a simi- 

 lar instance which lately led an eminent geologist to describe 

 crystalline limestones in this region as overlying unconformably 

 the gneisses. The phenomenon, in the writer's opinion, is one 

 which he has elsewhere described at length, namely the occur- 

 rence of great calcareous veinstones, wiiich hold the characteristic 

 minerals of the adjacent interbedded limestones, and like granitic 

 and metalliferous veinstones, have been deposited from solutions 



* This note is an abstract of a paper read before the American Asso- 

 ciation for the Advancement of Science, at Saratoga, in August, 1879, 

 but, through an oversight, not then published. As it contains some 

 matters of interest to geologists, I send the note as then written, with- 

 out change, to the Canadian Nafuralist. — T. S. H , January, 1883. 



