The Geology and Economic Geology of the Cranbrook District, British Columbia. A San Diego Fauna in the Newhall Quadrangle, California

Citation

Rice, Harington Molesworth Anthony (1934) The Geology and Economic Geology of the Cranbrook District, British Columbia. A San Diego Fauna in the Newhall Quadrangle, California. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/FK7Y-Y341. https://resolver.caltech.edu/CaltechTHESIS:03082018-080922171

Abstract

The geology and economic geology of the Cranbrook district, British Columbia:

The following paper embodies the results of four months spent in making a geological reconnaissance in the vicinity of Cranbrook, British Columbia in 1932 under the aegis of the Canadian Geological Survey.

Definite evidence is presented to show that the Wisconsin ice-sheet in the lower parts of the area, stagnated, broke up, and melted away in situ; a phenomenon which, as far as the writer is aware, has not been reported so far from the margin of the sheet. The erosive power of the ice appears to have been strictly limited, in contrast to the tremendous erosion which is accomplished over most of British Columbia. Evidence is also presented suggesting a pre-Wisconsin period of glaciation.

A detailed description of the stratigraphy and structure is given with particular emphasis on the pre-Cambrian (Beltian) succession.

A series of pre-Cambrian sills and dykes are described in detail. Border phases rich in ferromagnesian minerals and quarts are present and their origin by differentiation of the magma and assimilation of silica from the intruded quartzites is suggested and critically discussed. The sills are found to contain a species of hornblende differing considerably from any that has been described in the literature, and its chemical and optical properties are given in detail.

Mineralization is believed to have taken place at two periods; one in the pre-Cambrian and one in the late Mesozoic or early Tertiary. The evidence for this opinion is presented in detail and examples described. Some of the ore-bodies of pre-Cambrian age are believed to be magmatic segregations and the evidence in support of this belief is stated and discussed.

The geological history and the physiography is outlined and three theories as to the origin of the Rocky Mountain Trench briefly considered.

A San Diego fauna in the Newhall quadrangle, California:

During the summers of 1917, 1918, and 1919 Dr. William S. Kew undertook the mapping of an area to the north and west of Los Angeles. The area included a thick section of the Fernando formation which Kew was able to sub-divide into two formations, the Pico, lower Pliocene in age, and the Upper Pliocene and Pleistocene Saugus. Later workers in the Pico to the east of Pico Canyon and elsewhere split the formation still further until the following sub-divisions, as summarized by Grant and Gale, p. 32, were reached.

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