I became quite excited by the description of Shay #4, hoping that it had somehow ended up in Colorado... Alas, it would appear most likely that this picture was indeed taken on Mount Tamalpais (which is just north of San Francisco); #4 was scrapped in 1931 after the railway closed. I am glad see this picture. Thanks for sharing!
--"The first image shows Engine Number 4 – a Shay-type Locomotive. Although similar to locomotives used on the Argentine Central near Silver Plume, Colorado, Charles Albi discovered that this engine was actually used by California's Mt. Tamalpais & Muir Woods Railroad."