 | (Map site 1.) Roadcut exposure of gneiss along Big Tujunga Canyon Road. The age of this gneiss is not known, but it has to be older than the oldest igneous rock that intrudes it, the Wilson Diorite dated at about 120 million years old.
 | (Map site 2.) Alluvial fan emptying out of Delta Canyon into Big Tujunga Canyon. The volume of sand and gravel washing out of Delta Canyon is more than can be easily washed away by the river in Big Tujunga Canyon, so the alluvial fan that has formed at the mouth of Delta Canyon has forced the river to go around it.
 | (Map site 3.) The most abundant rock on today's trek is the Wilson Diorite. It consists mostly of quartz diorite, an igneous rock of medium gray color. It has been dated at about 120 million years old.
 | (Map site 4.) Closeup of the Wilson Diorite. Quartz diorite normally consists of mostly plagioclase feldspar with minor amounts of quartz, biotite, and hornblende. The pink mineral in this view is orthoclase feldspar, so this exposure is likely a local variant of the Wilson Diorite into granite.
 | (Map site 5.) Intruded into the Wilson Diorite is a granite that has been dated at about 90 million years old. This photo shows a typical roadcut exposure of the granite, which is commonly lighter gray than the Wilson quartz diorite.
 | (Map site 6.) Closeup of a slightly weathered specimen of the granite. Crystals are of rather uniform size and consist of feldspar (white), quartz (glassy gray), and a minor amount of biotite.
 | (Map site 7.) Another exposure of the granite. This one has a finer grained and more resistant dike intruded through it at the top of the photo.
 | (Map site 8.) A lens of gneiss occurring within the Wilson Diorite near the end of the trail revealed this small, tight fold in the gneiss.
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