Evidence from study and mapping of erosional levels, from reconstruction of dissected drainage divides, and from geological relations of a volcanic series proves that the Kern River has always followed a southerly course in its cutting in the Kern River Basin, refuting the deductions of Lawson (1904) that the Kern flowed eastward from the upper Kern Basin across Toowa Valley. Structural control of the Kern River by the Kern Canyon fault is shown to have been effected at the beginning of the older of two cycles; principal evidence is found in the plotted erosional surfaces preserved throughout the basin. The Great Western Divide is established as the primary division of drainage in the southern Sierra prior to the development of the Sierra Nevada fault. A hitherto unrecognized period of canyon cutting is recorded by channels cut in the Chagoopa level, now buried by flows, but visible in the walls of Little Kern gorge. Volcanism, in two stages, and periodic movement on the Sierra Nevada fault stagnated and diverted drainage in both tributary and master streams.