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Prologue: Today's continuing tour of the big ditch of northern Arizona gets a bit heavy given the theoretical explanation of how this chasm came to be a chasm. (Part 1'st diary can be found here: http://www.dailykos.com/...) As always, I will find a way to make the information more discernible without having to dumb things down, that is, in what the Buddha called spoon feeding to the sangha (community). Besides, I'm writing these diaries to one of the most overall erudite audiences on the planet; and somewhat akin to the folks I have had the pleasure to work with over many years, most of whom came on tours I conducted to learn something behind the scenery. Hence, not the usual tourist types desiring less talk and more sightseeing. Then again, why not do both at the same time, n'est-ce pas?
The Classic ‘Fairytale’ Version: Most people visiting the Grand Canyon see the Colorado River winding its way from the northeast to the southwest and assume this great chasm was cut and carved by this very body of water. However, the association of this assiduous river and the canyon is a common myth. As previously mentioned, the more involved story tells us otherwise. The most held theory, however, is that the Colorado did indeed make the first breach into the upper crust of the Colorado Plateau, then gradually incised its way downward into the sedimentary terrain. In time, erosion and faulting fabricated the exposed rock formations viewed today. So, in a way the Colorado River did initially breach the plateau in this region. Then again, the rest of the story unfolded through gradual uplifting, downcutting and erosion over time. To envision the regional landscape before this erosion and fabrication began, think of a huge slab of sedimentary material. If it's an uneven and bumpy sample, so much the better. Now expand the dimensions to nearly 2,000 square miles. You soon get an idea of what this region once looked like––a rather bland depiction long before the chasm and nexus of smaller canyons were created. When the waters of, what would one day become, the Colorado River first trickled down from the Rockies, then gradually turned into a more potent stream, its invigorated gnawing eventually flowed out of today’s Colorado territory, then wandered into the desert terrain beyond. No one can pinpoint when the river first arrived in the Four Corners vicinity. Neither can it be stated with any certainty what this body of water was doing for millions of years. About the only thing geologists can figure is the approximate time when the Colorado finally migrated toward the Echo and Vermilion Cliffs region, relatively close to today’s Page (Arizona). From there, it meandered and incised its way across a virgin territory now named the Marble Platform. Remember that the river, like all rivers and streams throughout the territory, could not inscribe its path so deeply without the great uplift of the Colorado Plateau (URL's for this trinity of diaries posted in yesterday's diary). In short, without uplift of the terrain, there could be no downcutting by rivers or streams into the pavement foundation.
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