Last Ranch in Hells Canyon by Queeda Mantle Walker Further Adventures of the Mantle Family. A Cattleman, Charley Mantle, Homesteaded in Hells Canyon - the place of his dreams - in 1926, and lived there with his wife, Evelyn. This magnificent, isolated canyonland located in the very northwest corner of CO was eventually discovered by the National Park Service. Dinosaur National Monument was created, and it enveloped the Mantle Ranch. The Monument's imposed restrictions, regulations, and interference with Charley's ability to make a living off the land with his cattle herd plagued him relentlessly. Queeda Mantle Walker was born on the Mantle Ranch. She now lives with her husband, Rex Walker, in Boulder, CO.