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, preceded only by Hayden's very rare separately published Snake River and Montana, and Wyoming Territories maps (Marcou & Marcou 629 & 630). 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.

The map is accompanied by the original report which includes "Map of a Military Reconnoissance of North Western Wyoming" (30.3 x 17.3") and 49 untitled maps which show the route of the reconnaissance. 8vo, rebound in modern maroon and grey library buckram with marbled endpapers.

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

Condition: B

The vividly colored geologic map has toning along the folds with three 1" fold separations along a horizontal fold. The "Map of a Military Reconnoissance of North Western Wyoming" is completely severed along a horizontal fold with several other small separations and a 3" binding tear at lower left. The other untitled maps are good to very good with light toning and an occasional fold separation. Text is clean and bright and new binding is excellent.