Though the recommendation of Professor Baird, the 16-year-old Merriam was appointed as naturalist of the Hayden Geological Survey of 1872. In June 1872 Congress had appropriated another $20,000 for completion of the notable Hayden Geological Survey of 1871. It had contributed to the founding of Yellowstone National Park. Both were part of the United States Geological and Geographical Survey of the Territories (1871-1877). Beginning in Ogden and the Wasatch Mountains of Utah, the expedition pushed between the Teton Basin and up through Idaho, Wyoming, and Montana and into the newly established Yellowstone National Park.