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San Gabriel Fault


vertical fault

Parking for San Gabriel Fault

  • Take the 210 to Sylmar
  • Take Exit 8 toward Osborne Street
  • Follow signs for Osborne Street/Foothill Blvd
  • Turn left on Osborne Street and head north (Note: Osborne St. becomes Little Tujunga Canyon Rd)
  • After 5.4 miles, pass by the Wildlife Waystation
  • After another 2.8 miles, pass over Dillon Divide
  • Keep going, pass over a small bridge and by several houses
  • When the road starts to climb, be on the lookout for a hairpin turn that has, on the right-hand side of the road, a wooden frame that used to hold an interpretive sign. Park here (you'll need a parking permit - see below).

Be on the lookout for poison oak!

To park anywhere within the National Forest, you need a US Forest Service Adventure Pass. They cost $5 a day and can be bought on-line or at various vendors.

At the site, walk on a crude trampled path back under a huge live oak tree, about 30 meters (100 feet), where you'll find a cliff amphitheater that has a nice waterfall in early spring. If you stand close to the east side (or scramble up the east hillslope a bit), you have a spectacular view of the San Gabriel fault (vertical black line) on the vertical western cliff face, separating light-colored "Josephine granodiorite" on the left from dark-colored "Mendenhall gneiss" on the right.


vertical fault

San Gabriel Fault

From 13 million years ago until 4 million years ago, everything south of the San Gabriel fault slid, earthquake by earthquake, a total of about 40 km (24 miles) to the northwest. At that time, the San Andreas fault did not exist north of the San Gabriel mountains; rather, the San Gabriel fault was the main fault. The San Gabriel fault is almost surely fully extinct now.

Something about the mystery of the black layer!

vertical fault

Close-up of San Gabriel Fault - note thin black layer in between

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Last updated: October 2, 2009 :: Contact Us


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