Latitude: N 34°25'10"
Longitude: W 117°54'00"
Number of Bench marks: 70
Number of Surveys to 2000: 16
Date of Initial Survey: 22 June 1978
Date of Latest Survey: 10 August 1989
Trespass Permission: The line is on private ranch property:
Ranch Manager, Carol Robinson
12880 Juniper Hills Road
Pearblossom, CA 93553
From Palmdale, proceed east and sout heast 27 miles to Pearblossom, thence south about 5 miles on Longview Road to its southernmost point which is at a fence and gate into the Mountain Glen Ranch. The first bench mark is on the north side of the fence about 2 m west of the gate. The line pr oceeds southward along the west side of the dirt road that leads up the creek on the ranch property.
This line crosses the Punchbowl fault along the northwest bank of Pallett Creek, six miles south of Pearblossom. It was established to determin ed if a swarm of earthquakes in the Juniper Hills area during the late 1970s was having an effect on the Punchbowl fault.
A plane recently crashed into the Pallett Creek level line area. The road that the level line follows was widened to allow heavy equipment access to the crash site. Many bench marks were bulldozed out, crushed, or pushed farther into the ground. This li ne needs to be restored before another survey can be done.
The first and latest levelings in the period 1978 to 1989 are compared in an accompanying figure with marginal evidence for about 1.5 mm of vertical displacement across the fault. The sense of displacement is mountain side down, and the location of the fault at the base of the high San Gabriel Mountains would pond g roundwater south of the fault. Thus, the sense of displacement is opposite to what one would expect from the recent geologic uplift of the mountains or from the lowering of the water table north of the fault during the 1986-1991 drought.
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