At the convergence of the states of Colorado, Utah, Arizona, and New Mexico lies the red rock country of the Colorado Plateau. The magnificent canyonlands of the region are the natural result of centuries of erosion by rivers, with their tools of suspended sand and gravel, and by heat and cold and rain. Relentlessly through the ages the rivers have carved the Plateau, exposing to our view the records of departed deserts and seas. Algal flats and small...