erosion

My conclusion... our little scarp is the result of mudslide and subsequent erosion by Del Puerto Creek. :)

In geomorphology, a terracette is a type of landform, a ridge on a hillside ... formed by soil creep or erosion of surface soils exacerbated by the trampling of livestock such as sheep or cattle. Synonyms (not preferred) are: catstep, cattle terracing, sheep or cattle track.

That's the San Joaquin / Orestrimba thrust fault, which marks the boundary between the central valley and Diablo Range / coast range geologic province. That's an ancient fault line associated with subduction and its corollary to the north, the Stony Creek Thrust, mark where the Franciscan zone subducted beneath the edge of N America, back in the day.

Fault contacts in the northeastern Diablo Range, California, between the partially mélanged late Mesozoic Franciscan Complex and the broadly coeval, less deformed sedimentary rocks of the Great Valley sequence have been called, by definition, the Tesla-Ortigalita fault. "Coast Range thrust" is the name applied by Bailey and others (1970a) to the fault of regional extent that originally separated subducted oceanic crust and sedimentary rock of the Franciscan Complex from structurally overlying ophiolite plus shelf-slope facies sedimentary rock of the Great Valley sequence. The two faults are not equivalent. High-angle Neogene segments of the Tesla-Ortigalita fault truncate older fault surfaces of the Coast Range thrust-fault system. Franciscan metamorphic rocks contain low-to high-pressure, low-temperature mineral parageneses characterized by the phases pumpellyite, prehnite, aragonite, lawsonite, glaucophane, and jadeitic pyroxene. Metamorphism has been variously ascribed to metastable re-crystallization, metasomatism by fluids generated in and around serpentinite, structural burial produced by subduction of an oceanic lithospheric plate, and burial plus tectonic overpressures generated beneath the Coast Range thrust fault. Suppe (1970) and Ernst (1971a) argued against metastable recrystallization and metasomatism on the basis of available field and laboratory evidence. If metamorphism is related to serpentinization, a metamorphic aureole should surround ultramafic bodies undergoing present-day ser-pentinization. Metamorphism resulting from tectonic overpressures generated beneath the Coast Range thrust fault will be revealed by an increase in metamorphic grade toward the thrust, whereas structural burial would result in an increase in metamorphic grade with structural depth. Distribution of mineral parageneses in the northeastern Diablo Range, revealed by analyses of more than 300 thin sections of metaclastic rocks, shows no spatial relation between highest grade rocks and either exposed segments of the Coast Range thrust fault or the margins of ultramafic masses undergoing present-day serpentinization. Thus the available evidence fails to support the metastable recrystallization, metasomatic, and tectonic overpressure concepts. Only the hypothesis of structural burial is not negated by the observed relations.

tradster, how about Gorman to Lebec

Yes when you put those mountain cows on flat ground they just walk around in circles!

The Melones Fault Zone (MFZ) is an important structure recognized in the Mother Lode district to the south, where it represents a major fracture of the foothills fault system of the western Sierra Nevada Mountains separating Mesozoic rocks to the west from Paleozoic rocks to the east. It is likely a conduit that tapped auriferous solutions at great depth during tectonic deformation in the geological past. Gold and silica (quartz) rose from these depths in the Mother Lode district as illustrated by some mines in the district that reached depths as great as 5,000 feet. It is likely that much of this gold was derived from the serpentinites of the MFZ.