The basin of the Colorado, excepting that part below the mouth of the Virgen and a portion among the “parks” of the western slope of the Rocky Mountain range, is almost entirely a plateau region. Some of the plateaus are very dry; others rise above the arid zone and are well watered. The latter are called the “High Plateaus.” They reach an altitude of eleven thousand feet above the sea. They are east of the Great Basin, and with the other plateaus form an area called by Powell “The Plateau Province.” Eastward still the plateaus merge into the “parks.” The High Plateaus, as a topographical feature, are a southern continuation of the Wasatch Mountains. They terminate on the south in the Markagunt, the Paunsagunt, and the Aquarius Plateaus. The extreme southern extremities of the two former are composed of mighty precipices of columnarly eroded limestone called the Pink Cliffs. Here is the beginning of the Terrace Plateaus, likewise bounded by vertical, barren cliffs. Between the High Plateaus and the parks, the plateaus may be called, for convenience, Mesa Plateaus, as they are generally outlined by vertical cliffs. This is the case also south of the end of the High Plateaus where, stepping down the great terraces, we arrive at the region immediately adjacent to the Grand Canyon, composed of four plateaus, three of them of mesa character, the Shewits, Uinkaret, Kanab, and Kaibab; and up at the head of Marble Canyon a fifth, the Paria, while still farther to the north-eastward is the Kaiparowitz. The edges of these Mesa Plateaus, precipitous cliffs, stretch for many miles across the arid land like mountain ranges split asunder. This region, lying between the High Plateaus, the Grand Wash, the Henry Mountains, and the Colorado, is perhaps the most fascinating of all the basin. The relief map at page 41 gives the larger part of it. In the basin there are also great mountain masses, the fountainheads of the waters which have carved the canyons. These are Uinta, Zuñi, San Francisco, Henry, Pine Valley, Uinkaret, Beaver Dam, Virgen, Navajo, La Sal, and others, some reaching an altitude of more than twelve thousand feet. The highest peaks of these, and of course those of the Continental Divide on the east, which furnish a large proportion of the water of the Colorado, and the Wind River Mountains on the extreme north, have snow-banks throughout the summer. To show how dependent the Colorado is on the high peaks for its flood-waters, I will mention that it is not till the snows of these high altitudes are fiercely attacked by the sun in May and June that the river has its annual great rise. It would take only a slight lowering of the mean annual temperature now to furnish these peaks with ice caps. The rainfall in the lower arid regions is from three to ten inches, increasing northward to fifteen and twenty-five. On the peaks, of course, it is much greater. Almost any climate can be had, from the hot arid to the wet frigid. On the