"This valley for the most part is wide and open." There are "spurs separating it from the Hell-Gate Valley on the south," and "separate on the north the various tributaries flowing into the Blackfoot River." Plate LXII.
Exploration party moving up the Sun River valley "in the direction of the pass between the Crown Butte and the Rattlers, prominent landmarks west of Sun River and visible at a great distance." Plate XXIX.