FIGURE 3.4.-Schematic block diagram of part of the Coast Ranges of California, showing gross structural relations between principal lithotectonic units cut by the San Andreas fault (modified from Irwin, 1977). The Coast Range ophiolite lies at base of the Great Valley sequence and is separated from underlying Franciscan rocks by the Coast Range thrust. Blueschist-facies metasedimentary and metavolcanic rocks that form border zone in the Franciscan immediately below the thrust are not shown. View southeastward along the San Andreas fault.