A blow up of this photo is in an article about the Breckenridge coal dock in Jan2013 B&Lpp12-13.The C.H.Scott photo showing the incomplete dock is dated as ''circa 1897''.There is a follow-up article on p27 of the April issue.
This photo of Cooke C&S number 49 has been published in several books, but is usually cropped, leaving out some good stuff at the right frame.
The photo dates from 1906-1907, judging from the lettering scheme of the locomotive.
This is about the only view I've seen of the track side of the Pitkin coal chutes. Just as in Joe Crea's drawings of the Pitkin chutes, the trestle bent posts are all vertical and appear to be piles instead of square timbers.
Looks like both a boxcar and a stock car are being used to deliver coal for locomotive use.