Considered by archaeologists to be on the northernmost portion of the Mogollon People's sphere of influence, the Gila Cliff Dwellings National Monument is home to two prominent ruins sites among a collection of smaller sites located within the Gila Wilderness inside the Gila National Forest. The Monument landscape ranges in elevation from around 5,700 to 7,300 feet above sea level and follows the branches of the Gila River. The terrain around the ruins is rugged and arid, and contains steep-sided canyons cut by shallow spring rivers and mesas and bluffs forested with Ponderosa pine, Gambel's oak, Douglas fir, New Mexico juniper, pinon pine, and alligator juniper (among others). The area geologic history stems from the Oligocene epoch and volcanic activity that subsequently covered the area with ash. The Monument's hot springs are remnants of this volcanic history.