We did stop for a few moments to look over a rejuvenated brook, and I took a closer look at the rock surfaces, which consisted mostly of metamorphic greenstone and ultramafic serpentinite. My attention was drawn to the lichens on the rock surface, and I took some macro images. The lichens occupy a strange world we don't see all that often. They live on a different scale at the interface between rock and atmosphere. The acids they produce are one of the elements in the weathering and chemical breakdown of exposed bedrock.
Lichens are a complex symbiosis of algae and fungi. There are probably 500 different species in nearby Yosemite National Park, though only 100 have been so far cataloged. I have really only just begun to study these fascinating life forms closely.
Marshes Flat Road is a nice quiet avenue that crosses the high ridge east of Highway 49 between Coulterville and Chineses Camp. Paved, but mostly 1 1/2 lanes, it offers some nice views and excellent wildflower displays in the springtime.