HUNTINGTON AND GOLDTHWAIT: THE HURRICANE FAULT. 253 
far enough to produce the young and vigorous topography of JJ. The 
hard Carboniferous strata, A’, have been but little affected except in the 
immediate river valleys, where deep narrow canyons, J’ and H!, have 
been cut with very precipitous sides. The overlying soft strata, B’, have 
been entirely stripped off except where they are buried under lava and 
form mesas, G', or where they are protected by the Shinarump, C’. In 
the same way the Painted Desert strata, D’, have been removed, and the 
overlying hard Kanab, £’, forms cliffs. To-day these cliffs are rapidly 
retreating but erelong talus from the upper hard layers will so cloak 
the lower soft layers that the slopes will become more moderate and 
the retreat of the cliffs much slower. 
Figure 12. 
North-south sections to show the work of the present cycle. 
The best example of the stripping of soft strata is the great Carbon- 
iferous platform, in which is cut the canyon of the Colorado, Here, 
over an area of hundreds or even thousands of square miles, a few hun- 
dred feet of Moencopie shales have been stripped off, as is shown by the 
unconsumed patches remaining here and there, and by the larger masses 
preserved under lava caps. Although the most notable feature of the 
cutting of canyons is the Grand canyon, others, such as that of the Vir- 
gin river, are worthy of mention. An interesting case is that of Ash 
creek, which now flows in a shallow canyon at the foot of the Hurricane 
fault north of Toquerville. As this is part of the downthrown block, the 
amount of cutting has naturally been less than in corresponding cases 
on the other side of the fault. The notable feature, however, is that a 
short distance west of the present canyon is another of about the same 
size which is now dry and lies on the crest of an arched sheet of basalt 
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