HUNTINGTON AND GOLDTHWAIT: THE HURRICANE FAULT. 245 
the Colorado river, and unbroken by any elevation more prominent 
than a subdued escarpment a few hundred feet high. Nowhere in all 
the broad horizon was there anything sharp or abrupt in the relief. 
Everywhere maturity and old age were the rule, —a maturity of strong 
but unobtrusive outlines, whose mountains were domes and whose 
valleys were broad basins filled with gravel; an old age where relief 
had almost vanished. 
Lava Flows. 
Having reconstructed the topography as it existed at the end of the 
inter-fault cycle, we must put off the discussion of the last faulting long 
enough to mention a few facts connected with the lava flows which are 
so important as a means of preserving the ancient surface and of 
measuring the extent of recent displacements. When at last the time 
arrived for the land to wake from its Jong rest and once more begin an 
active life of uplift and growth whereby it might enter a new cycle and 
renew its youth, the first warning of impending change came in a series 
of lava flows, the precursors of a long line of which the last was poured 
forth but yesterday. Our observations agree with those of Dutton 
and others in showing that lavas were often ejected many times from 
what seems to be the same vent. In some cases there appears to have 
been no great interval between successive flows, since there is no notice- 
able evidence of weathering and erosion to differentiate them. In the 
fault scarp above Bellevue, for instance, a section has been exposed in 
which are at least ten thin sheets of basalt that seem to have been 
poured out in comparatively rapid succession. At St. George, on the 
other hand, is one of the best examples of a very different type (Fig. 
11). Just west of the town rises a broad flat-topped mesa of Painted 
Desert and Kanab sandstone capped at an elevation of five hundred 
and fifty feet above the town by a sheet of basaltic lava, A. On the 
east side of this, about three hundred and fifty feet below the top, lies 
a terrace a few hundred feet wide which, like the mesa, owes its preser- 
vation to a cap of basalt, B. The general level of the country on either 
side is now more than two hundred feet below the terrace. On the 
valley floor to the west is a third sheet of lava, C. All three of these 
flows seem to have come from a point a few miles to the north, al- 
though it is not known whether they are all derived from the same 
source. They represent the great difference in age which prevails among 
the products of volcanic eruptions, even though all may rightly be called 
VOL. XLII.— No. 5 4 
