Colorado River may have pooled and spilled over to form the Grand Canyon, solving a long-standing mystery — but not everyone agrees
The Colorado River may have carved out the Grand Canyon after pooling as a giant lake in what is now northern Arizona and spilling downstream, a new study suggests. Scientists found that tiny sediment grains in the Bidahochi Basin, upstream of the canyon, were carried from the upper Colorado River watershed by 6.6 million years ago. The findings fill in a 5 million-year gap about where the Colorado River was during this early period, said John He, a geologist at UCLA and the first author of the new study, published today (April 16) in the journal Science. … The findings, in turn, suggest that a giant ancient lake in the basin slowly filled and overflowed, causing the Colorado River to flow through and carve out what is now the Grand Canyon around 5.6 million years ago.
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