Latitude: N 35°22'16"
Longitude: W 117°51'03"
Length: 1002.7m
Number of Bench marks: 60
Number of Surveys to 2000: 7
Date of Initial Survey: 30 August 1984
Date of Latest Survey: 24 July 1996
Trespass Permission: None needed.
Directions:
From Mojave, proceed 20 miles northwest on Highway 14 to Red Rock-Randsburg
Road and turn right. Drive east for 8.7 miles to an unimproved dirt road
on the right that follows the southwest edge o f an ancient beach bar. Drive
0.5 miles on the dirt road to a railroad track. Cross the tracks and follow
the southwest edge of the beach bar to the first major gulch crossing. This
gulch intersects the level line.
Comments:
This is a box-shaped array across the Garlock fault, one mile southeast of
Saltdale. The southwest leg of the array is adjacent to the trench site described
by Burke (1979).
Results: Seven levelings in the period 1984-1996 are compared in an
accompanying figure and reveal from 20 to 100 mm of subsidence of part of
the southeast block relative to the northwest block. The subsidence of bench
marks in the southeast leg of the array may be due to the fact that they
are located in a thick sequence of unconsolidated lake beds. One may conclude
permissively that the southwest block has subsided relative to the northwest
block nearly 20 mm across the fault, but it is probable that it is related
to nearby pumping of groundwater for irrigation in Fremont Valley.
References:
Burke, D.B., 1979. Log of a trench in the Garlock fault zone, Fremont Valley,
California. U.S. Geological Survey Map MF 1028.
Sylvester, A. G., 1992. Nearfield interseismic vertical strain on the central
Garlock fault, southern California, 1984-91. Geophysical Research Letters
19 (10), 1037-1040.
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