Geologic Structures in Northern California as Detected from ERTS-1 Satellite Imagery

Preliminary structure contour map of the Sacramento Valley, California, showing major late Cenozoic structural features and depth to basement

“…The Cohasset Ridge fault can be traced north of Deer Creek through an intensely fractured zone in the Tuscan Formation to the vicinity of Mill Creek where it becomes obscured by a complex pattern of west and northwest-trending arcuate faults that are shown in generalized fashion on the map. Although the area south of Deer Creek is heavily forested and the slopes are covered by a veneer of colluvium, the trace of the Cohasset Ridge fault is defined by a prominent topographic linear, observed by Rich and Steele (1974), that extends nearly to Magalia where it apparently is intersected by the Magalia fault.…”

Tectonic controls on magmatism and geothermal resources in the Geysers-Clear Lake region, California: Integration of new geologic, earthquake tomography, seismicity, gravity, and magnetotelluric data

“…3) all appear to be significant northeast-trending faults associated with an extensional environment. Rich and Steele (1974) identified a system of north-northeast, discontinuous linears confined to the central core of the Coast Ranges in The Geysers region which are easily seen on ERTS (Earth Resources Technology Satellite) imagery; one set being coincident with the northwestern boundary of our extensional zone as jointly constrained by all of the various types of data. Rich and Steele further speculate that these are the youngest system of geologic features in the Coast Ranges except for the San Andreas Fault.…”