A clash of seasons An early autumn snowfall in the higher elevations of Mullan Pass surrounds Austin Creek Trestle (a.k.a. Skyline Trestle) at Skyline, Montana, on October 11, 1997. Lower elevations toward Helena received rain, but a frosting of snow sticks to the trees up on the pass, creating an unusual look to the scenery. A westbound Burlington Northern Santa Fe train is grinding up the grade with an A-B-A set of Cascade green BN power; SD40-2s Nos. 7070 and 7028 sandwiching GE B30-7AB No. 4107.