. The copper-bearing rocks of lake Superior / by Roland Duer Irving. Geology; Geology; Copper ores; Copper ores. ANIMIKIE BOOKS ON THUNDER BAY. 373 â quite large areas, filling corners between the feldspars. This rock is as near to the augite-syenites as to the orthoclase-gabbros.^ The smaller dikes, usually under twenty feet in width, are of a denser i-ock, the only section of which examined showed a very highly augitic diabase allied to the ashbed kinds. All of these dikes have a general northeasterly trend, but the amount of easting lessens as they are followed northeastward. This may be se
. The copper-bearing rocks of lake Superior / by Roland Duer Irving. Geology; Geology; Copper ores; Copper ores. ANIMIKIE BOOKS ON THUNDER BAY. 373 â quite large areas, filling corners between the feldspars. This rock is as near to the augite-syenites as to the orthoclase-gabbros.^ The smaller dikes, usually under twenty feet in width, are of a denser i-ock, the only section of which examined showed a very highly augitic diabase allied to the ashbed kinds. All of these dikes have a general northeasterly trend, but the amount of easting lessens as they are followed northeastward. This may be seen in a single dike in the case of the Victoria Island group of islandt,, which to the southwest trends N. 60° E. and to the northeast N. 52° E. Of the crystalline rocks interbedded with the slates, the greatest masses, often over a hundred feet in thickness, appear to be olivine-gabbros and orthoclase-gabbros, identical with the two kinds of rocks of the broader dikes. These masses beyond question are interbedded with the slates, and though no direct connection was seen between them and the dikes, from the nature of the rocks such a connection is probable enough. The rock â of the great mass capping the bluff just north of Sucker Brook, for instance, is an orthoclase-bearing gabbro very close to the dike rock of the mouth of Pigeon River, and on the same bluff, at a lower level, precisely the same orthoclase-bearing rock is seen cutting the slate, the probability being very strong that the two are connected. In thin section this rock shows labra- dorite, some orthoclase, abundant augite or diallage, partly much altered and partly in quite fresh, long, twinned blades, and very abundant magnetite in long, rod-like Fig. 33.âBed of intrusive diabase in Animikie slates, Pigeon Bay, Canada. Besides these greater imbedded masses, thinner, strongly cross-colum- nar beds of a dark crystalline rock are often seen. These are at times -only four to six feet thick. They ge
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectgeology, bookyear1883
