From the Santa Cruz State Parks web site:
William Page was born in New York and came to California in 1850
at the age of 18 to try his hand in the mines. He was quickly
successful and returned east to his home. He returned again to
California in 1852 to work in the gold fields. Although he was
unsuccessful in this second venture, he managed to get by. After
securing employment with a sawmill in La Honda, he went to Mayfield
(present day Palo Alto) and established his own lumberyard.
William Page was a skillful timberland manipulator, and by the
end of 1852 he was supplying logs to the mills of the Searsville
area, near present day Portola Valley. He built his own shingle
mill on Peter's Creek. Trees were selectively logged, and judged
suitable for shingles only if they very straight grain so they
could be split properly. He later moved the mill to Slate Creek,
just east of the present day Slate Creek Backpacking Trail Camp. He
established a haul road that connected the mills to the Embarcadero
in Palo Alto. This haul road was later named Page Mill Road and
still exists today though in a much-improved state.
I was really hoping for more than a sign after hiking for miles,
but that is all there is left here -- a flat spot and a sign.