NATURE OF PORTERVILLE CLAY, SAN JOAQUIN VALLEY, CALIFORNIA.

This investigation describes an area of typical Porterville clay, provides measurements of the linear expansion pressure, and expansion volume of the clayey soil, and gives the mineralogy, significance, and probable genesis of the clay and included nonclay aggregate material. In addition, the expansion pressure test results, using a modified California expansion pressure measuring apparatus, are arranged to show the correlation between expansion pressure and deflection of the clayey soil. The nature of the dominant clay mineral, montmorillonite, and the identification of the other soil minerals is presented, using X-ray diffraction, infrared spectra, and differential thermal analytical methods.