The Mogollon Rim offers some of the most stirring views on the planet.
But it’s not just 100-mile vistas, the undulations of forests and the billows of clouds that break against this more than 200-mile-long chain of tall cliffs rising up more than 1,000 feet in places.
In fact, the view from the long line of sandstone and limestone cliffs also offers a view of the violent history of a tempestuous earth — and a primer in the small changes that produce dramatic variations in the intricate net of life. It even offers clues as to how all living things might end.
This line of cliffs that mark the edge of the vastly uplifted Colorado Plateau runs from near Flagstaff all the way to New Mexico. The sheer layered cliffs are made from sand dunes and sea bottoms laid down, buried, compressed and then uplifted once more into sunlight and storm.
This state’s landscape and history have been dramatically shaped by this rampart of rocks, first fused before the first dinosaur cracked its shell (which came first, the dinosaur or the egg?).
The Mogollon Rim sharply divides the Sonoran Desert from the world’s largest ponderosa pine forest. It affects the climate of the region, forcing the release of snow and rain from passing storms — and in the process making Phoenix possible by filling up a chain of reservoirs. The Rim forms one of the most dramatic ecological divides in the country. It even bears mute witness to at least two terrible events that wiped out most living species on the planet.
Moreover, this jagged line of cliffs uplifted some 20 million years ago by the same shifts that created the Rocky Mountains offers a wonderfully diverse array of recreational options for visitors.
Start the story some 300 million years ago with the formation of the Kaibab Limestone found near the base of the Rim. This limestone formed in the bottom of a vast inland sea, well before the first dinosaurs emerged. Composed mostly of the skeletons of tiny sea creatures that drifted to form thickening layers over the millennium, this sea bottom layer extends to the Grand Canyon and north into Utah.
Movements of crustal plates that rearranged whole continents, driven by stirrings deep in the semi-molten layers of Earth’s mantle, eventually uplifted that one-time sea bottom, converting it into a vast interior desert on a scale to dwarf the modern Sahara or Gobi.
New shifts in the earth, some 250 million years ago, then buried the vast, cross-bedded sand dunes of that desert. The pressure and heat of the overlying rock layers fused those ancient sand dunes, creating thick layers now dubbed Coconino Sandstone. This buff, pale rock layer forms the bulk of the cliff face along the Rim, in addition to the upper layers of Sedona and great expanses of southern Utah.
On the pathetic scale of a human lifetime, the Earth seems patient and immutable. But on its own terms, the Earth is restless and given to violent outpourings. No sooner had the movement of the crustal plates buried those great sand dunes and turned them to stone than it once again shifted.
Pressured upward from below by some still mysterious shift, the great block of crust that includes the Rocky Mountains and Northern Arizona began an inexorable uplift between 80 million and 50 million years ago, creating a region known as the Mogollon Highlands. Rivers then flowed north, depositing thousands of feet of sediment stripped from the rising mountains in interior basins.
But the Earth can never quite decide.
So between 35 and 20 million years ago these titanic forces shifted once again, spurring a vast outpouring of lava — which put a cap of hard, resistant rock on top of the softer layers of sandstone and limestone.
All of that finally set the stage for the emergence of the modern topography of Arizona and the Colorado Plateau, starting about 20 million years ago.
Great blocks of earth resumed their uplift, this time, tilted to drain to the south. The layer of lava rock slowed erosion where it formed a cap, resulting in the dramatic march of cliffs, as the softer sedimentary rock went tumbling down the newly formed Salt and Verde Rivers and as the ancestral Colorado River chewed back north until it captured rivers once north-flowing rivers. This created the intricate topography of the Grand Canyon.
The process created the dramatic, 7,000-foot-high plateau atop the Rim, with its meadows, rainfall, snow cover, streams, great rolling forests and views to forever. It also created some of the most rugged, beautiful and inaccessible canyons in the country, draining the bounty of that rain and snow off the Rim to the 1,000-foot elevation of Phoenix.
Hikers have long marveled at some of those canyons, like West Clear Creek, Black River Canyon, Fossil Creek, Tonto Creek, the East Verde River, Pine, Sycamore, Oak Creek, Wet Beaver, Greenback, Salome, Sawmill, San Carlos and the immense gash of the Salt River Canyon — with world-class whitewater rafting during the spring thaw and the summer monsoons.
Many canyons remain guarded by cliffs and waterfalls that require rock climbing skills and a reservation permit to navigate. That includes Cibecue Canyon, which requires adventurers to rappel through two or three waterfalls in the company of a certified Apache guide.
This uplifted wall of lava-capped, fossilized sand dunes has shaped every aspect of the state’s history and ecology. It forms a boundary line for many plant and animal species, it controlled patterns of travel and settlement and controls the weather of the whole state.
The Mogollon Rim also bears mute witness to the violence and unpredictability of life. Coded into the layers of its sedimentary rocks lurk the evidence of two almost unimaginable catastrophes — geological eye blinks in which perhaps 90 percent of the land-based species abruptly vanished.
One of those events marked the end of the dinosaurs — which cleared the way for the current age of the mammals.
Ironically, the other mass extinction event layered into the face of the Mogollon Rim essentially cleared the way for the dinosaurs — by snuffing out perhaps 95 percent of all living species on both land and sea.
Scientists think that the already declining dinosaurs were done in by the strike of a gigantic meteor, which probably left the gigantic, telltale crater now buried in the mud off the coast of the Yucatan. Most scientists believe that impact shrouded the planet in a bone-chilling layer of smoke that lasted for years — plunging the whole Earth into a “nuclear winter” that wiped out every land-based species weighing more than 55 pounds.
One thin layer of rock in the face of the face of the Mogollon Rim contains the iridium-rich, melted droplets of stone and fractured “shocked quartz” deposited all over the planet as a result of that impact some 65 million years ago.
So the view from the Rim does in fact cover far more than 100 miles. From there, you can see all the way from the birth of mountains to the end of all things.