uurro.s-.] AGE OF THE CHASM. 119 



ous throng of craters. Very many wide and deep floods of basalt have 

 poured over the edge of the plateau into the lower Toroweap Valley 

 and upon the great esplanade of the canon, 1,500 to 1,800 feet below, 

 and, spreading out into wide fields, have reached the brink of the inner 

 gorge. Pouring over its brink, the fiery cascades have shot down into 

 the abyss and pursued their way many miles along the bed of the river. 

 At one epoch they had built up the bed of the Colorado about 400 feet, 

 but the river has scoured out its channel again and swept them all 

 away, regaining its old level, and is now cutting the sandstones below. 

 The spectacle of the lava floods descending from the Uinkaret, as seen 

 from Vulcan's Throne, is most imposing. It tells the story so plainly 

 that a child could read and understand it. Compared with many classic 

 volcanic regions the volcanism of the Uinkaret is a small affair. In 

 those classic regions the mind does not come into direct contact with 

 the enormity of the facts by a single glance of the eye. But here, if 

 kind Asmodeus were to lift the basaltic roof of the plateau, we should 

 see no more than we do now. The boldness of the picture is much in- 

 creased by the pediments of Carboniferous strata projecting from the 

 body of the plateau, showing the brilliant colors of the strata and their 

 sharply-defined architecture, with the dark masses of basalt wrapping 

 around them. Hard by, and almost within hail, is a superb gable pro- 

 jecting between two broad floods of lava, and so beautifully proportioned 

 and richly colored that we cannot help wishing to transport it by magic 

 to some more habitable region. 



The Toroweap Valley has a significance to the geologist which might, 

 not be at once apparent to the tourist. Even the geologist would be 

 slow to discern it unless familiar with cognate facts displayed in the 

 country at large bordering the Grand Canon. In the effort to interpret 

 its meaning it becomes necessary to take a hasty view of one or two broad 

 facts relating to the lateral drainage of the chasm. Upon the north side, 

 in all the distance between the head of the Marble and the foot of the 

 Grand Canons, there is but one side caiion carrying drainage from dis- 

 tant regions. This single exception is Kanab Canon. In this respect the 

 Colorado is much like the lower courses of the 2sile ; and the cause is 

 plainly the same. The region is too arid to sustain any living streams or 

 even to keep open the conduits which in former periods might have sus- 

 tained them. Yet upon the assumption that at some former period the 

 climate was much more humid all analogy compels us to believe that 

 the Colorado once received many tributaries which are now extinct, and 

 upon examination we find good evidence that this was really the case. 

 The Toroweap Valley is the modified channel of an ancient river. On 

 the west side of the Uinkaret is another. A third is seen upon the 

 south side of the Colorado, directly opposite the Toroweap ; and a few 

 others may be easily designated. It appears that all these rivers dried 

 up before the inner gorge was excavated. For if they had continued to 

 carry water we may be sure that they would have cut their chasms as 



