The Geology of a Portion of Humphrey's Quadrangle

Citation

Scott, David Holcomb (1939) The Geology of a Portion of Humphrey's Quadrangle. Bachelor's thesis, California Institute of Technology. doi:10.7907/WW5D-7S89. https://resolver.caltech.edu/CaltechTHESIS:12212009-135514171

Abstract

Two sedimentary formations are present in this area; the Modelo formation and the Mint Canyon formation. The latter sediments make up most of the rocks in this region while the former is confined to the southwestern one-fourth of the area. An angular unconformity separates the marine Modelo (Upper Miocene) from the non-marine Mint Canyon formation (Lower-Upper Miocene). The sediments are typical of those deposited under semi-arid conditions. Conglomerates, sandstones, and clays are abundant. There has been little local faulting, but folding is developed to a high degree, especially in the sediments of the Mint Canyon. Recurrent volcanic activity has taken place in Miocene time and several ash beds are interbedded in the sediments. The only other rocks present in the area are some uplifted terrace gravels of Quaternary age and the recent valley alluvium.

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