Great Salt Lake and Bonneville Lake sediments within Jordan Valley include thick sequences of clay with local sensitivities of up to 11. Much of this clay is predominantly illite and montmorillonite which was deposited in the saline waters of low level stages of Lake Bonneville. Clay mineralogy, pore water salinity, cation exchange capacity, carbonate contents, and organic carbon contents have been determined for relatively undisturbed cores and then correlated with sensitivity. The major factor contributing to sensitivity is expansion of the electric double layers of montmorillonite due to the leaching effect of moving, fresh ground water. The next most important factor is the deflocculation of clay particles by organic peptizing compounds, followed in importance by brittle cement bonds formed by precipitation of CaCO3. Linear correlation of sensitivity with an empirical combination of the key causal factors gave a correlation coefficient of 0.81 with a standard error of estimate value of 1.31. Deleting two samples, one containing a volatile organic fraction and the other containing undecomposed wood chips improved the correlation coefficient to 0.90. Application of the Gouy theory of interacting electric double layers to physico-chemical data obtained from clay is a valid means of identifying key causal factors controlling the mechanical properties of the clay-water system. In the lake sediments of Jordan Valley, sensitivity correlates significantly with the combined effects of ground water leaching, organic peptizing agents, and brittle cement bonds.

  • Supplemental Notes:
    • This article is an excerpt from the Proceedings of the Fourteenth Annual Engineering Geology and Soils Engineering Symposium that was sponsored by Idaho Transportation Department, Division of Highways; University of Idaho, Department of Geology and Department of Civil Engineering; Idaho State University, Department of Geology and Department of Engineering; and Boise State University, Department of Geology, and Department of Physical Science and Engineering. This symposium was held at the Rodeway Inn, Boise, Idaho, and was hosted by Boise State University.
  • Corporate Authors:

    Idaho Department of Highways

    P.O. Box 7129
    Boise, ID  United States  83707
  • Authors:
    • Buck, B W
    • Parry, W T
  • Publication Date: 1976-4-9

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  • Accession Number: 00142674
  • Record Type: Publication
  • Created Date: Feb 1 1977 12:00AM