Since the time of Major Powell's thrilling exploration of the Grand Canyon, the history of the Colorado River has been the subject of many papers by American geologists. Out of them has grown a general interpretation that is now widely accepted. Differences of opinion relate chiefly to the details of the story rather than to the major ideas.
While studying the valley of the Colorado River and its tributaries, between the mouth of the Grand Canyon and the Mexican border, I have been led to the conclusion that two current opinions about the history of the river are untenable. One relates to only a part of the river's course; the other concerns the river system as a whole. The lesser of these problems will be examined first.
In his reconnaissance of the Colorado River valley, Lee1 found a long trough in northwest Arizona, . . .