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Geology of a Portion of the Southern Sierra Nevada of California: The Northern Kernville Quadrangle

Citation

Webb, Robert Wallace (1937) Geology of a Portion of the Southern Sierra Nevada of California: The Northern Kernville Quadrangle. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Q1CF-3G40. https://resolver.caltech.edu/CaltechTHESIS:11112019-171107969

Abstract

The northern Kernville quadrangle lies on the great central plateau of the southern Sierra Nevada in Tulare, Kern, and Inyo counties, California. It comprises about 600 square miles.

Geomorphically, the area consists of a great interior platform, bounded on the east by the Sierran escarpment and Sierra Nevada fault, and on the west by the Main Fork of the Kern river. The region is divisible into nine geomorphic provinces, each with distinct characteristics. From west to east, these are: (a) the Greenhorn mountains, a range averaging 7000 feet in elevation, whose summits are remnants of an ancient erosional level, (b) the Main Fork valley, a pronounced north-south valley of 3000 foot depth, traversing the entire quadrangle, (c) the Meadowlands, a high, rolling old-land, remnant of an old erosional surface, (d) the South Fork canyon, (e) the Rockhouse basin, (f) the Crestal Upland, which marks the eastern crest of the Sierra Nevada, (g) the South Fork valley, a wide, alluvia ted east-west valley, which bisects the area in an east-west direction, (h) Kiavah mountain, and (i) Piute mountain. The origin of each of these subdivisions is discussed. It is shown that a complex series of events produced the present geomorphic features. The region has undergone plantation, rejuvenation in at least two epochs, and subsequent erosion to the present time. A geomorphic history attempts to harmonize all recorded events.

Structurally the region contains the important Kern Canyon fault, which parallels the Main Fork of the Kern for a distance of more than fifty miles, although not strictly coincident with it. It is shown that the Kern Canyon fault is of very ancient date, probably pre-Pliocene, also that a high fault-line scarp is eroded along the Kern Canyon fault. Evidence is presented to explain the discordance of the Main Fork of the Kern river with the fault. It is suggested that superposition by alluviation prevented the river from taking a course along the fault, as the stream was revived.

Petrologic and field studies in the area show the following rock units to be present: (1) a series of metamorphic rocks of probable Carboniferous age, classed as the Kernville series, composed primarily of quartzites, phyllites, schists, and marbles; these are invaded by (2) an horn-blende-gabbro to biotite-gabbro, which is closely associated with (3) a quartz-diorite, which invades the gabbro. The date of emplacement of these units is suggested as late Carboniferous. (4) The Isabella granodiorite, varying to granite, invaded all the other formations, and is the final important intrusive unit. This invasion probably accompanied the major diastrophic disturbance of the Sierra, generally set at late Jurassic to early Cretaceous. Tertiary and Quaternary lavas preserve erosional surfaces formed across the crystalline units. Some swamp and lake deposits, together with present and older alluvium, complete the petrologic sequences.

Economically, the region has few deposits of commercial importance. Gold and barite have been mined commercially. Future production is improbable.

Item Type:Thesis (Dissertation (Ph.D.))
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:1936
Record Number:CaltechTHESIS:11112019-171107969
Persistent URL:https://resolver.caltech.edu/CaltechTHESIS:11112019-171107969
DOI:10.7907/Q1CF-3G40
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:13567
Collection:CaltechTHESIS
Deposited By: Melissa Ray
Deposited On:12 Nov 2019 01:33
Last Modified:20 Dec 2019 20:04

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