A serious question about the Grand Canyon's origin

[dougettinger]

In a recent discussion about the Grand Canyon I was made aware that no river made the canyon which supposely originated from the drainage of an inland sea through faults in the mountains. The entire elevated region surrounding the Grand Canyon was covered by an ocean whose crust raised in a single event. This ocean then drained from the rising plateau to a new sea level via the side canyons and the main canyon. The estimated 600 side canyons are huge in themselves and generally start with 100 foot ledges or waterfalls from the top of a 5000 to 6000 foot elevation which I can personally attest with my own visits to the area.

What explanation do geologists or planetary scientists give for this unbelievable event ?

Doug Ettinger
Pittsburgh, PA

[Chris Peterson]

In a recent discussion about the Grand Canyon I was made aware that no river made the canyon which supposely originated from the drainage of an inland sea through faults in the mountains. The entire elevated region surrounding the Grand Canyon was covered by an ocean whose crust raised in a single event. This ocean then drained from the rising plateau to a new sea level via the side canyons and the main canyon. The estimated 600 side canyons are huge in themselves and generally start with 100 foot ledges or waterfalls from the top of a 5000 to 6000 foot elevation which I can personally attest with my own visits to the area.

What explanation do geologists or planetary scientists give for this unbelievable event ?

That is not correct. The canyon was cut by the Colorado River. Like all such river canyons, the increased erosion was primarily the result of uplift in the surrounding region (as opposed to the river cutting down). In the case of the Grand Canyon, the Colorado Plateau underwent rapid uplift during the Laramide Orogeny (which also formed most of the present day Rocky Mountains). The rate of formation of the Grand Canyon was not uniform, but depended on periods of varying uplift and changes in the Colorado River flow from ice melt and other climatic factors.

I don't know any geologists who would describe this as "unbelievable". There are many similar river canyons all over the world; the Grand Canyon simply happens to be the largest. Different uplift mechanisms are known. Uplifts in the center of the North American plate, however, are not completely understood. The Laramide Orogeny occurred when the Atlantic Ocean first started developing, and it is speculated that a combination of reduced volcanism at the Pacific/North American boundary, a shallow subduction angle at the same boundary, and increased spread at the Mid-Atlantic ridge caused the center of the North American plate to buckle upwards.

This is an ongoing area of geological research. I have several colleagues who study volcanism and other mountain building processes in the American West in an effort to better understand uplift in this region.

[dougettinger]

Your understanding and also my own previous understanding is that the uplift mechanisms occurred over long periods of time.

However, a realization has just come to mind. The huge 600 side canyons end abruptly with 100 foot ledges and waterfalls at the top of the plateau. There are no gentle branching of a tributary system that is known for most rivers. If you experimented with a large tub filled with water with its bottom covered with packed soil, and release a drain plug from the bottom on one side, one could produce the same effect as the Grand Canyon's side canyons. A different effect is achieved by releasing water just above the soil packed inside a large tub from a hose at a certain rate at the opposite end of the tub's drain.

This recent discussion did make me think about a single event that occurred over a short period of time. Of course, geologists prefer to think in terms of events causing unusual geological formations as occurring slowly enabling mankind to react and save himself from extinction. But there do exist reasons in the minds of geophysicists for quick movements (a span of days) of large regions of the Earth's crust. However, these reasons require a major paradigm shift in thinking about reality even though evidence for this shift is staring at us.

Doug Ettinger
Pittsburgh, PA

[Chris Peterson]

Your understanding and also my own previous understanding is that the uplift mechanisms occurred over long periods of time.

The total uplift of the Colorado Plateau happened over a long time, perhaps 3000 meters over 50-60 million years. But the uplift rate has not been constant. There have certainly been periods of very rapid uplift- as much as hundreds of meters per million years. I don't think there is anything inconsistent with this understanding and the observed geomorphology. Keep in mind that there have been many large flood events in the canyon, including many in the last few tens of thousands of years, as the last glacial period ended.

[dougettinger]

I understand the dating of rocks, estimates of times counting the number of cycles to create a certain amount of layers in sedimentary rock, the dating of fossils in the rock, etc. But, how are times estimated for spans of time to uplift a mountain range, even different periods of uplift rates?

The great flooding that occurred from the giant glacier melting in the northern latitudes went via the Columbia, St. Lawrence, and the Mississippi River Basins. The flooding of the Grand Canyon could only have resulted from the glacier melting of the central and southern Rocky Mountains. Would this flooding have been ample enough to create the Grand Canyon and please let's not forget the side canyons ?

Doug Ettinger
Pittsburgh, PA