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Show 286 GEOLOGY OF THE HIGH PLATEAUS snows. Early in autumn the snows have disappeared and the lakes cease to outflow, but never dry up. The length of the Aquarius from northeast to southwest is about 35 miles, and its breadth from 10 to 18 miles. Its altitude varies from 10,500 to 11,600 feet above sea-level. Over three-fourths of its periphery is bounded by massive cliffs, while along the remaining fourth it declines gently to its confluence with the Awapa. Its upper portion is a lava-cap of vast dimensions, varying from 1,000 to 2,000 feet in thickness. Its lavas are seen in greatest mass at the northwestern flank, overlooking the southern part of Grass Valley and the Panquitch Hayfield. Upon the southern and eastern sides, at the foot of the volcanic wall, the long slopes begin, which reach far out into the mesas of the inner Plateau Country. Their descent is slow and easy to all appearance, but they are deeply gashed with profound canons and terrible gorges, among which it is dangerous to venture. To traverse these slopes it is necessary to keep high up near the base of the lava-cap, where the ravines head, and where they are sufficiently open to afford a practicable trail. Even here the journey around the base of the cliff is laborious, involving the constant ascent and descent of vast gorges and amphitheaters, and requiring many days to accomplish it. Yet the traveler who has abundant strength and perseverance will be amply rewarded, provided he has chosen his way with prudence and good judgment. Upon these slopes the structure of the plateau is revealed. In truth, there is but little " structure." The plateau is simply a remnant left b}^ the erosion of the country around its southern and eastern flanks. A few of its minor features are due to displacements, and its western wall originated in a great fault or rather in several faults. The rest of the mass owes its pre-eminence to circumdenudation. We may gain some notion of the stupendous work which has accomplished this result by taking our position upon the southeastern salient at the verge of the upper platform. It is a sublime panorama. The heart of the inner Plateau Country is spread out before us in a bird's-eye view. It is a maze of cliffs and terraces lined off with stratification, of crumbling buttes, red and white domes, rock platforms gashed with profound canons, burning plains barren even of sageâ€"all glowing with bright color and flooded with blazing sunlight. |
