Hi Ted-
The Santa Cruz, Big Trees & Pacific is the standard-gauge line which runs during the Spring and Summer from Felton to Santa Cruz using the CF-7s. This line was originally built in the early 1870s as a narrow-gauge line and known as the Santa Cruz & Felton. Later on in that decade, Fair and Davis purchased the railroad and it became the last leg of the South Pacific Coast to Santa Cruz. The entire line was standard-gauged by the Southern Pacific (first a 3-rail operation for 3' and standard gauge trains, and ultimately the 3rd rail was removed). The standard-gauging began in the mid-1890s if I remember correctly from a Los Gatos history book...and completed after the 1906 earthquake. I'm not sure as to when the SPC ceased to exist; the SP bought it out long before the name faded off into history. The line from Olympia (north of Felton) to Los Gatos ceased operation after 1939; the tunnels blasted, and the tracks removed after a storm. Trains stopped running in Los Gatos in 1959 in the form of a GP-9 and two 'subs'. The tracks were taken back to Vasona Junction; and from there to Olympia, it's just a memory. Lexington Reservoir obliterated 'Cat's Canyon' above Los Gatos Creek when the creek was dammed up. The line through downtown Los Gatos is mostly undeveloped on the south side of Route 9 and is paved over for much-needed parking in town. The rest of the line has been pretty much built over by University Avenue above Lake Vasona, and many of the businesses between N. Santa Cruz and University near the park. Vasona Park and Oak Meadow Parks are home to the 18" gauge Billy Jones Wildcat Railroad...which doesn't run Venice Railway #2 right now. Billy Jones worked the 'mountain line' from the SPC days in the 1890s until the end, before going to the Daylight out of San Francisco; when he discovered the #2 and ran it at his ranch until 1968.
I'm sure you probably knew that and I just spewed some useless local history information on my part. The narrow-gauge Roaring Camp & Big Trees line, which is steam-powered, is all-new; but I did hear something of part of the line being a spur of the SPC or SC&F. This is, to my knowledge, unsupported; but I don't know. Jeff Badger or Phil Reader can set that one straight I'm sure.
Technically, the Ardenwood/Carter Brothers group up near Fremont (Newark) is closer to the Bay Area. This is home to ORIGINAL South Pacific Coast rolling stock. Trains are pulled by horses, or diesel 'critters'. George Thagard's "Deanna" has run in September for the past few years; and previously, Richard May brought the Hawaii Railway #5 in 2000. I missed it; though I was given plenty of notice when visiting the NCRy in another part of Fremont.
Bruce MacGregor has connections with that group, and he also lived (or still does) for many years in Los Gatos. I also understand that with the new Town Plaza renovation project that a memorial set of rails was put into cement to commemorate the railroad...
-Ed Kelley