128 TRANSACTIONS OF THE [May 23, 
(vol. ii, p. 475), and the recent mining excitement in the vicinity 
of Deep Creek, a station on the old pre-railway stage route, has also 
prompted a brief sketch from W. P. Blake (Age of the Limestone 
Strata of Deep Creek, Utah, etc., Amer. Geol. Jan. 1892, p. 47, re- 
printed in the Eng. and Min. Jour., Feb. 27, p. 253). It appears 
that one of the Basin Ranges, the Ibapah, runs along the borders 
of Utah and Nevada, and consists in a large degree of limestones 
which Blake regards as Lower Carboniferous from the specimens of 
Productus contained in them. These are pierced by granite and 
other igneous rocks which have wrought extensive contact meta- 
morphism in the limestones, and caused the formation of some 
interesting minerals briefly noted by Blake. Evidently the igneous 
rocks also pierce slates, as is shown by the following description of 
slide No. 6. 
No. 1 of dike adjoining claim near Fish Spring Camp is rhyolite. 
It shows a microcrystalline ground-mass with some glass, abundant 
idiomorphic phenocrysts of quartz, a crystal or two of sanidine, and 
a very little biotite, sometimes bleached. Rhyolites have already 
been recorded by Emmons from the region. 
No. 2, from a granite outcrop that forms the mass of Clifton 
Mountain near Gold Hill, isa hornblende granite with considerable 
plagioclase, and with apatite, and titaniferous magnetite. 
No: 3, an altered limestone from Monaco, near Clifton, showed 
more physical than mineralogical changes. 
No. 4, from the American Desert, between Dugway and Fish 
Spring, and about three miles east of Fish Spring, i is a hypersthene- 
andesite of great beauty. The ground-mass is glass, with a few 
little plagioclase needles. The large plagioclase crystals are zonal 
and often full of inclusions of the eroundmass. A grain or two of 
magnetite appear. Almost the only other mineral is hypersthene, 
in rounded prismatic crystals, of strong characteristic pleochroism, 
and in great abundance. The extinction is invariably parallel, and 
the optical properties such as would be expected. One stray augite 
was also detected. 
Hypersthene was strangely overlooked by Zirkel in his report for 
the 40th Parallel Survey, “but has been announced by Iddings to be 
quite widespread in the voleanic rocks of the Great Basin and the 
Pacific Slope." Cross has also described an interesting occurrence 
in the Buffalo Peaks,? Colorada, and in the paper has given a quite 
complete review of the known localities for these rocks in other 
parts of the world. Up to the publication of his paper they were 
but few and often questionable. 
No. 5, from two miles east of Rockwell’s Ranch, Cherry Creek, 
is another andesite of different character. It has large brown 
1 Hague and Iddings, Notes on the Voleanoes of Northern California, Oregon, 
and Washington Territory. A.J. 8., Sept. 1883, p. 222. Also Volcanic Rocks 
of the Great Basin, idem, June, 1884, p. 453. 
2 C. W. Cross, Bulletin No. 1, U. S. Geol. Survey. 
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