Went hiking on Mount Tamalpais today. It's a fine mountain, very close to San Francisco yet peaceful and serene, especially on a weekday. I covered seven miles or so, hiking above the marine inversion; you get fine views of the top of the overcast, shrouding the ocean and the city, while you're in clear air above the smog and haze. The vegetation is a mixture of fir, juniper, fern, and madrone. A distinctive rock, serpentine, is seen all over the place near the summit of Mt. Tam; it has a greenish hue, and areas where it is prevalent are more lightly vegetated than surrounding spots since firs don't grow where serpentine prevails. The basic pluses of hiking Mt. Tam are fine views and solitude, as well as good exercise. It's a Bay Area institution.