"Arizona's Grand Canyon"
Title: Arizona's Grand Canyon (Plateau Magazine, Vol 62/2)
Author: Dorothy A. House
Publication Date: 1991
"Nine stories about the magic of the Grand Canyon. "Arizona's Grand Canyon" From the moment the current of the river catches your boat at Lee's Ferry, you know something extraordinary is happening. "The View from Below, The View from Above" There are deeper canyons in the world. Perhaps there are longer ones. But nowhere is there a gorge as large overall. "Ecological Diversity" The topography of Grand Canyon National Park has a remarkable range of elevations, from 9,000 feet at the top of the Kaibab Plateau to 1,200 feet at the lowest river level. Climate varies accordingly. "Geological Wonder" The staggering amount of solid rock gouged away; the span of time recorded in exposed rock walls; the unimaginable forces that over a billion years ago buckled, mashed, and melted the somber rock of the inner canyon-all of this focuses attention on the dynamic planet that created and sustains us. "Ribbons of Rock" The Grand Canyon story begins in the late Precambrian, 1.7 billion years ago, when shales and volcanic rock created in an off-shore environment were slammed into the continent and then folded and buried in a violent episode of mountain building. "Erosion" Since it is a hard rock, the Kaibab Limestone held fast when erosion swept away most of the softer Mesozoic layers above it. But even the Kaibab could not resist the cutting power of the Colorado River. "Canyon Maker" Visitors are often surprised by the Grand Canyon's youth. Rocks exposed in the walls of the Grand Canyon are very old. But the canyon itself is relatively young. "The River" Within the canyon, the Colorado River ranges in width from 80 to 300 feet. Between Lee's Ferry and the Grand Wash Cliffs, it drops about 2,000 feet in elevation. "The Challenge of the Canyon" We shackle to the river, the great canyon maker. We disrupt age-old cycles. We even create and destroy ecosystems. Still man's impact on the Grand Canyon pales when compared to the impact the canyon can have on us."