Page:Popular Science Monthly Volume 53.djvu/27

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thousand feet more, with the production of a narrow gorge having precipitous walls, not yet widened into a mature valley. Channels like that of the Colorado also occur crossing submarine plateaus.

PSM V53 D027 Valley of the rousseau dominica.jpg
Plate II.—Valley of the Rosseau, Dominica. A short, deep valley, heading in an amphitheater and dissecting a denuded plateau.

The short tributaries of these high plateau valleys may be likened to gigantic washouts. Such short, deep valleys commonly form at their heads amphitheaters, which may be a few miles in length, as is illustrated in Plate II. These are sometimes so precipitous