A handsome and colorful map that illustrated the report of T.B. Comstock, the geologist to the Military Reconnaissance of the region that was conducted by Capt. W.A. Jones, Corps of Engineers. This is one of the earliest geological maps of Yellowstone country based on actual exploration, preceeded only by Hayden's very rare separately published Snake River and Montana, and Wyoming Territories maps (Marcou & Marcou 630 & 629). Chart shows 15 classes of geology, the topography and trails in the northwestern part of Wyoming, including roads, stage stations, military posts, astronomical observation stations and boundaries of the Snake Indian Reservation. Area includes Jackson Hole, the Big Horn and Teton Mountains, and extends south to Fort Bridger and the Sweetwater Mountains. Terrific detail of the newly formed Yellowstone Park.

References: Marcou & Marcou #631; Blevins Mapping Wyoming #256

Condition: B+

Folding, as issued. Some toning along folds, and some faint offsetting. A fold separation repaired with archival tape on verso.