Franciscan rocks in The Geysers Geothermal Resources Area (GRA) constitute a greatly deformed and chaotic assemblage of rocks known as melange which, under natural conditions, poses problems to slope stability. Unstable conditions inherent in the melange are accentuated by the steepness of slopes, chemical alteration of the rocks, and numerous faults and shear zones. Adverse effects that may be .experienced- with development of melange terrain can, however, be mitigated if potential problem areas are recognized before development begins and if good engineering geology·and engineering practices are followed.