This is the exact same lichen as two other pitures featured elsewhere (http://bit.ly/p76e4K and http://bit.ly/o76PpT), but unlike those two this has diffuse, even lighting applied.  I like the other two better, and am posting this one primarily as a contrast.  A brown-fringed gray foliose lichen overgrowing at least three other morphologies of lichen on a rock.  I believe the primary lichen has numerous isidia (small finger-like structures protruding from the thallus).  My best guess is that this is in _Physcia_, but I'm not sure.  This lichen was found in Vasquez Rocks County Park in Los Angeles County.