Note 310 — OREGON MISSIONS AN OUTLINE SKETCH OF OREGON TERRITORY AND ITS MISSIONS (continued 4)
Reading edition
No stream named “Arrowstone” is now charted. De Smet passed from the waters of the Columbia to those of the Missouri, by one of the numerous low and easy gaps between Mullen’s on the north and Deer Lodge on the south. Probably the party went over Cottonwood (or Peterson) Pass, leading from Deer Lodge County into Jefferson, coming out upon Boulder River, which empties into the Jefferson at Jefferson Island; or else they followed the Silverbow route past the present Butte, and proceeded by Big Pipestone Creek to the Jefferson—a route now used by the Montana railways. All these were well-worn Indian trails.—Ed.