Mogollon Rim

Originally called the Mogollon Plateau, the Rim is one of the most striking geographic features in Arizona. Running across the state from the southeast to the northwest, it is most prominent in the area in northern Gila County. The top of the Rim varies from 6500 to over 7500 feet above sea level and the country below the Rim is almost 1000 feet lower. When I was young, I had no idea how to spell the name because it is pronounced "muggy-on" by most of the locals. Later, I learned that the Rim was in reality the edge of the vast Colorado Plateau. It took me a while to put all of the geography together, because in the area shown above, the cliffs do not look at all like the sandstone of the Four Corners area. Most of the rock is a weathered green rather than the striking pinks and reds of the canyon country to the north. But, notwithstanding its appearance, the Rim is still mostly sandstone and limestone.

When I was young, the Rim was a wild and lonely place with almost no roads and those that did exist were dirt or mud when it rained. We could go for hours without seeing a car or another person while traveling along the Rim. Now, with a number of wide highways crossing the Rim country, it is not only accessible but crowded on many days during the summer. There are still areas of solitude, but the wilderness atmosphere is long gone.

The top of the Rim, and most of the land below the Rim is one vast Ponderosa Pine (Pinus ponderosa var. scopulorum) forest, said to be the largest Ponderosa Pine forest on the continent. OK, now what that really means is that the other large forests in North America just have different types of trees, usually because they have more water. Even though this huge forest is green and inviting, it is really a desert forest. Annual rainfall amounts are well below most other large forested areas. Quoting from the Land Use History of North America, Colorado Plateau from Northern Arizona University,

Before European settlement, widespread surface fires that occurred every 2-15 years favored grasses and limited pine densities. Early explorers described majestic, open stands with rich grasses and occasional shrubs beneath, as young ponderosa seedlings were often killed by the low-intensity fires while mature pines, with their thick yellowish red bark, were only scarred. The effects of grazing and fire suppression since the late 1880s on ponderosa pine forests have been profound, including a shift to forests with very high tree densities, which in turn has contributed to destructive forest fires. Separate web pages give more detail on ponderosa pine fire ecology and reintroduction of fire to forest ecosystems. Two longer research essays, Changed Southwestern Forests: Resource effects and management remedies, and Restoring Ecosystem Health in Ponderosa Pine Forests of the Southwest are also available in this website.