. Annual report. 1st-12th, 1867-1878. Geology. GEOLOGICAL SUEVEY OF THE TERRITOEIES. 39. WEATHERED GRANITES AT MADISON CANON. tliickness of black micaceous gneiss, with seams of wMte quartz, the coarse feldspathic granites, literally an aggregate of large crystals of quartz and feldspar, then underneath the black gneiss Fig. 7, again. In this canon there is a most interesting illustration of the weathering of the red- dish feldspathic granites by the peeling off in thin concentric layers, or as I have denominated it in my former reports, disin- tegration by exfoliation. I have never observed a
. Annual report. 1st-12th, 1867-1878. Geology. GEOLOGICAL SUEVEY OF THE TERRITOEIES. 39. WEATHERED GRANITES AT MADISON CANON. tliickness of black micaceous gneiss, with seams of wMte quartz, the coarse feldspathic granites, literally an aggregate of large crystals of quartz and feldspar, then underneath the black gneiss Fig. 7, again. In this canon there is a most interesting illustration of the weathering of the red- dish feldspathic granites by the peeling off in thin concentric layers, or as I have denominated it in my former reports, disin- tegration by exfoliation. I have never observed a more marked example anywhere in the West, and Fig. 7 shows it well. After passing through the canon a distance of about three miles, the road bends to the north, leaves the valley of Stinking Water, passes over a high divide to Alder Gulch, in which Virginia City is located. On the right or east side of the road, the rather rounded and, in some instances, grass-covered hills, continue all the way. On the left or west side, the gneiss and quartzite continue for a short distance, when the mountain range, which has hitherto walled us in on the west side of the road, bends a little to the northwest, and extends to the Jefferson Valley, parallel with the Stinking Water, and rises quite abruptly, 2,000 feet above thechannel of the stream. The base of this ridge or range is a smooth lawn-like slope, down to the margin of the stream, while the ridge itself is composed of massive beds of limestone inclining 60° to 70^*, the outcropping edges projecting sharply on the summits, and the northeast sides sloping down into the plain, like a very steep roof. The valley itself is a beautiful and fertile one, and is one of the numerous valleys that open into the Jefferson Fork. It will average from four to six miles in width and about twenty miles in length below the canon, and is covered with a moderate thickness of the Pliocene deposits. On the east side of Stink- ing Water, the rocks are en
Size: 1886px × 1325px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1860, bookpublishe, booksubjectgeology
