Lees Ferry's rock units have funneled human activity into the region for thousands of years. It sits at the geological juncture of the Precambrian and Paleozoic world of the Grand Canyon below and the Mesozoic world of the Colorado Plateau above. Beginning with his prehistoric kin, next with the Spanish and the early explorers and colonists, and right up through today's tourists and river-runners, man has made good use of the geology in travelling through the region.
THE NAVAJO BRIDGES(S)
Floating downstream from Lees Ferry, the river appears to drop quickly as it carves its way into the
The still-narrow gorge doesn't permit these Permian formations to separate into their classic stairstep topography. These formations are far thinner here than to the west and actually pinch out to the east of Lees Ferry, since the Permian Kaibab and Toroweap Formations originated in vast seas to the west of the primitive North American continent. River guides will remind you to say goodbye to these formations, since you won't see these rock layers again near the river as you raft through the Grand Canyon. You'll only see them high up at the rim.
Realizing the importance as both a crossing and boat-launching location, immediately below Lees Ferry the canyon of the Colorado River becomes impenetrable, where the resistant limestones of the Kaibab and Toroweap Formations rise quickly and form the vertical walls of
In 1903 David Rust, a Stanford educated schoolteacher turned trail builder, began developing a layover point for hunters and sightseers at the present day location of Phantom Ranch known as Rust's Camp. In 1907 he built a cable- tram across the Colorado River, which was essentially a harrowing ride in a suspended metal cage. On his way to hunt mountain lions on the North Rim, Teddy Roosevelt used the tram in 1913. In 1921 a wooden suspension bridge was built to replace the tram. It allowed mules to cross the river but was narrow and swayed violently in the wind.
From this lofty perch one can see both bridges spanning the Colorado River, as it makes a sweeping turn flowing to the west. The Black Bridge is in the foreground and the Silver Bridge is beyond. The South Rim is in the distance with the lower bench representing the Cambrian age Tonto Platform. The cliff below it comprises the Inner Gorge and consists of the Grand Canyon Metamorphic Suite, made up of the Early Proterozoic, dark Vishnu Schist and the lighter-colored, pinkish-intrusive rocks of the Zoroaster Granite.
The gorge exposes an extraordinary cross-section of the Proterozoic orogen between the central Arizona Transition Zone and the Rocky Mountain region. The gorge consists of several lithotectonic blocks that were primarily active during the 1.7-1.6 Ga accretion and stabilization of the Yavapai and Mojave crustal provinces.