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The Geology of a Portion of Humphreys and San Francisquito Quadrangles


Gombotz, Joseph John (1939) The Geology of a Portion of Humphreys and San Francisquito Quadrangles. Bachelor's thesis, California Institute of Technology. doi:10.7907/3MMF-ME33.


The rocks of this area range in age from the pre-Cambrian Pelona schist to the Recent alluvium. This metamorphic formation is separated from the two sedimentary formations by a formation of two igneous intrusives, which have been faulted into their position between the Pelona schist and the Sespe (Oligocene?) formation, the igneous rock, granodiorite and leucomonzonite, caused the extreme tilting of the Sespe when they were faulted into their present position. These rocks are probably of Jura-Cretaceous age. The Sespe is a thick series (approx. 4000 ft.) of continental deposits, now in a more or less consolidated condition. The Lower Upper Miocene Mint Canyon formation is another continental: series deposited unconformably upon the Sespe. It consists, in the lower section, of coarse conglomerates, sandstones and shales with some ash beds in the upper part which show some volcanic activity during Upper Miocene times. The region then underwent some folding and gentle tilting in post- Miocene times and a mature land surface was formed. There was a deposition of terrace material in probably Pleistocene time after which the region suffered continuous uplifting until the present time.

Item Type:Thesis (Bachelor's thesis)
Subject Keywords:Geology
Degree Grantor:California Institute of Technology
Division:Geological and Planetary Sciences
Major Option:Geology
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Unknown, Unknown
Thesis Committee:
  • Unknown, Unknown
Defense Date:1 June 1939
Additional Information:San Francisquito Quadrangle is misspelled in in original title as San "Fransisquito".
Record Number:CaltechTHESIS:12172009-094322384
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:5457
Deposited By: Tony Diaz
Deposited On:11 Jan 2010 19:43
Last Modified:22 Feb 2023 22:22

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