File:Transactions (1871) (14753769956).jpg

Identifier: transactionsmining27amer (find matches)
Title: Transactions
Year: 1871 (1870s)
Authors: American Institute of Mining, Metallurgical, and Petroleum Engineers
Subjects: Mineral industries
Publisher: New York (etc.)
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: University of Toronto

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, and there may besome question whether it represents it or the gabbro-gneiss.Along the highway the Orchard gneiss runs to the west of thegeneral line of the Barton gneiss, and appears also to the north-ward beyond the actual pits. East of the northward extensionof the highway that passes next the little pond, gabbro is ex-tensively developed, and, as drawn on the map, it forms a largehill to the eastward. Still further to the northeast, near thelittle hamlet of Fletcherville, the relations of the gabbros andacidic gneisses are again very complex, and are not taken uphere. On its east and south sides this hill has been productiveof much ore, from the Cook shaft and the ONeill shaft. Bothare quite deep, are now abandoned and are therefore inaccessi-ble. The dumps show, however, both basic and acidic gneisses,as is the usual rule. The ores in character and geological posi-tion correspond to the Mineville group rather than the Bartongroup. GEOLOGY OF THE MAGNETITES NEAR PORT HENRY, N. Y.
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GEOLOGY OF THE MAGNETITES NEAR PORT HENRY, N. Y. 189 The greatest geologic interest attaches to the interpretationof the nature of these constituent gneisses. The followingbrief summary is an endeavor to set forth the certainties andthe most reasonable inferences : 1. The foliation or gneissoid development is most promi-nently shown in those rocks that are rich in dark silicates..These are the gabbro-gneiss and the Barton gneiss. It almostfails in the others. In the gabbro-gneiss there is little doubtthat it has been developed in an otherwise massive plutonicrock by dynamical processes, such as shearing and viscous flowunder pressure. The foliation of the other gneisses has prob-ably originated in the same way, but that they were originallyplutonic or other igneous rocks is less clear, although it is theconviction of the writer that they were. This question is anobscure one, on which, however, chemical analyses might throwsome light. 2. The foliation, although more or less irregular,

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