Return to Interstate 8 and proceed east to the Kitchen Creek exit. Turn right (south) to the intersection with Old Highway 80. Continue east on Old Hwy 80 to its intersection with the La Posta truck trail (about 1.3 miles). Park under bridge.

No picture for this one... (not terribly photogenic!)

The riprap under the bridge was taken from the H-B facies in a freeway outcrop about a kilometer to the west. Zircons extracted from this outcrop gave a U-Pb age of 93 ± 1 Ma. The rock is unfoliated with sharply euhedral crystals of hornblende, biotite and sphene. Modal analyses indicate a tonalitic composition with sparse alkali feldspar oikocrysts. The corresponding H-B facies on the east side of the pluton is somewhat more mafic. The transition from the H-B facies into the L-B facies occurs just over the ridge to the west and is 50 to 100 m in width. The weathered rock under the roadway and in the outcrop on the east side of the road is in the L-B facies.