At the west end of Rocky, Colorado, a westbound Union Pacific empty coal train climbs through Little 10 Curve. On the perfectly clear afternoon of June 9, 2014, the city of Denver is easily seen above the highlighted rocks of the Laramie Formation. It’s 6:47 p.m., and in only a few minutes, the sun will set low enough that shadows from the Front Range of the Rockies to the west will creep across the fill.
