Identifier: annualreportofun1711geol (find matches)
Title: Annual report of the United States Geological Survey to the Secretary of the Interior
Year: 1880 (1880s)
Authors: Geological Survey (U.S.)
Subjects: Geological Survey (U.S.) Geology Water-supply Forest reserves Mines and mineral resources
Publisher: Washington : G.P.O.
Contributing Library: University of Illinois Urbana-Champaign
Digitizing Sponsor: University of Illinois Urbana-Champaign

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according to theshape and size of the components. As in other portions of the SierraNevada, foreign material occurs, mixed with that of volcanic origin.This fragmental andesite attains a thickness of more than 700 feet onthe plateau east of the head of Bear Creek, and about the same thick-ness on the northeast part of the Mooreville Bidge, where it distinctlyOverlies the older basalt. About 1 j miles south of Cammel Peak, in the canyon of Pall River,is a dike-like mass of fragmental andesite. The stream has cut intothis dike of andesite-breccia to the depth of about 500 teet, and in thedike material in the bed of the river are embedded numerous frag-ments of fossil wood, as well as pebbles of pre Cretaceous rocks andpebbles and fragments of hornblende andesite and of the older basalt.The pieces of wood must have been washed into this tissure from thesurface, together with the andesitic material in which they are embed-ded. The specimens of wood collected were referred to Pro). F. II.
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TURNER.) TERTIARY VOLCANIC ROCKS. 569 Knowlton, who reports that it is a Sequoia of the redwood, or 8. sem-pervirens, type. The wood is not well enough preserved to enable me tosay that it is the same as the living redwood, although it is undoubt-edly near it. This dike like mass is about 1,500 feet in width wherecrossed by Fall River. The wall rock is granite. As usual, however,the writer was not the first to note this occurrence. The place was vis-ited by Professor Pettee1 in 1879, but he made no investigations as tothe nature of the dike. The fine-grained hypersthene-andesite noted in two previous publica-tions2 is found in the Bidwell Bar area, so far as known, only at FranklinHill and at one other point. At Franklin Hill it forms a cap havinga maximum thickness of 300 or more feet on the north slope. Thecharacteristic slaty structure of this lava is well brought out at thisplace, and a photograph was taken to show the feature, which is repro-duced in PI. XXI. The second locality

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