Mount Tamalpais, California, USA
(c) 2003 Andrew Alden, licensed to About.com, Inc. (fair use policy)
Tamalpais or "Mount Tam" is the essential landmark of Marin County, the idyllic country just north of San Francisco. It's also known as Sleeping Lady and is visible over most of the Bay area. From the top of Tamalpais you can see the Sierra Nevada and a great deal else.
Most of Marin County is east of the San Andreas fault and consists of Franciscan rocks, a shorthand term long used by California geologists for the mixed assemblage of marine metavolcanic and metasedimentary rocks, once a subduction complex, that was dug up and torn to pieces by the Tertiary reorganization of the North American plate margin. (The first part of my California Subduction Tour goes through this area.) On the other side of the fault is Point Reyes, a chunk of Salinian rocks carried here from hundreds, perhaps thousands of kilometers to the south.
This view is looking north at Tamalpais from the tidelands of Mill Valley. The peak on the western side is actually the highest point, but a military communications site was put there and now it's off limits. The fire roads running down Tamalpais's forested flanks were the birthplace of mountain biking. Marin County may be ridiculed as a land of rich sybarites, but the people there work hard and play hard.