The Geologic Setting of the John Day Country: Grant County, Oregon

"The Geologic Setting of the John Day Country: Grant County, Oregon" by Thomas P. Thayer is a comprehensive scientific work, probably from the mid-20th century, that examines the geologic history of Oregon's John Day area. It explores the geological features of the region, renowned for its natural history and fossil beds, by detailing the geologic development of the area starting over 250 million years ago, covering volcanic events and sediment deposition. It also includes a road log designed to guide readers through significant geological sites. It educates about the geologic processes that have sculpted John Day Country, turning it into a site of scientific interest and outdoor recreation, and emphasizes important features such as the John Day River, volcanic formations, ancient life, and the effects of glacial action.