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University of California Publications. [Geology 



On the west of Little Valley the same order of fault-block 

 motion is recorded. From the Slide Mountain east- west faint 

 south the high west ridge continues unbroken to the line of the 

 important east-west fault. This first portion is, however, curved, 

 with its concave side facing Little Valley. South of this line 

 are a number of small blocks whose position is outlined in topo- 

 graphic forms. The Snow Valley Peak area is regarded as a 

 solid block which has moved upward. The relatively sunken 

 areas of Little Valley and Marlett Lake occupy portions between 

 fault-blocks that have been spread apart laterally. The whole is 

 very expressive of a compressive force acting between extreme 

 north and south points. In fact, no other explanation seems 

 adequate to explain the facts. Further, Slide Mountain and 

 Snow V alley Peak represent elevated blocks, whose upward 

 movement must have produced a compression in a north-south 

 direction. Such force was necessary to produce the buckling of 

 the low east ridge at the point west of Franktown where the 

 plateau remnant abuts against the high west scarp, the shearing 

 action that occurred at the two northeast-southwest faults, and 

 the striking instance of the shortening of the high west ridge 

 southeast of Incline. Also the fact that the two ridges bound- 

 ing Little Valley are lowest at points midway between the centers 

 of elevation of the same forces. There is strong supplementary 

 evidence also of the compressive stress set up by the elevation 

 of the two peak blocks, in the form and structural features of 

 the hanging block in north Little Valley. This block, occurring 

 at present as a series of small blocks, lies between the point where 

 the plateau remnant east of north Little Valley abuts against 

 the steep west scarp and a second point east of the upper 

 entrance to Franktown Creek canon. There is evidence of a 

 plane of fracture at this point in the high west ridge, along 

 which but little differential motion seems to have occurred. The 

 south end of the hanging block is between 400 and 500 feet 

 above the valley floor, so that at least that much of a cross-fault 

 has occurred there to form this boundary of the block. The 

 north end of the hanging block joins the low east ridge where 

 the plateau remnant rests against the west scarp, thus proving 

 the original identity of its level top with the old erosional sur- 



