LOST LAKE Level Line

Latitude: N 34°16'34"
Longitude: W 117°28'00"

Length: 1169.7m
Number of Bench marks: 33

Number of Surveys to 2000: 7
Date of Initial Survey: 18 July 1985
Date of Latest Survey: 22 July 1994

Trespass Permission: Permission to trespassis required from property owner.

From the intersection of Interstate 15 and Hwy 138, take I-15 south 0.5 mile to Cleghorn Road turnoff. Follow Cleghorn to the south (on the frontage road) 1.9 miles to Swarthout Canyon Road, thence right (west) and follow the road to the left, cross the r ailroad tracks. At a point 0.8 mile from the tracks (?) bear to the right at a "Y" in the road. Cross the tracks again and the paved road will become a dirt road. At 0.7 mile from the second track cross ing, proceed northwest on a dirt road that leads to the right. At 0.25 mile from the right turn, over the fault scarp and on top of a river terrace, is the beginning of the level line. The first bench mark is LL01.

This is a box-shaped array across the San Andreas fault 100 m northwest of Lost Lake and 2 km south of Cajon Junction, in Cajon Pass.

Three levelings of the array are compared in an accompanying graph. Bench marks southwest of the fault and along Swaggart Canyon Road, spec ifically from LL16 to LL22, have risen a couple of millimeters relative to those in the remainder of the array, but the uplift is still within one standard deviation of the allowable uncertainty

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