DAVIS: THE GRAND CANYON OF THE COLORADO. al 
and squash (a, p. 96). Even within the crystallines of the Shivwits 
block, small side streams of ‘‘ gentle slope” are reported by Wheeler as 
entering the main river and forming boulder rapids, but no mention is 
made of falls at the stream mouths (pp. 166, 167). Plate XVII., in 
Dutton’s Monograph, reproduced from a photograph, shows two side 
canyons entering the narrow inner gorge of the main canyon just east 
of the Toroweap, and joining the main river in accordant fashion. Evi- 
dently, then, hanging valleys have no important place in the Grand 
canyon; and the hanging lateral valleys of the Alps, whose floors are 
five hundred feet or more above the open flood plains of their main 
valleys cannot be explained by normal river erosion. 
Some striking examples of hanging valleys in a very narrow canyon 
are, however, described by Gilbert in the case of the North fork of 
Virgin river in southern Utah, where it cuts through the massive 
Triassic sandstones. This narrow defile is many times deeper than 
broad ; its walls are nearly vertical and parallel for the greater part 
of their height, but they depart sufficiently from the vertical, now to 
this side, now to that, to hide the sky from the adventurous observer 
who follows the narrow, boulder-strewn stream bed. ‘‘ The side cafions 
all partake of the character of the main, but, being worn by smaller 
streams, are narrower, and their bottoms are of steeper grade. Many of 
them at their mouths are not cut so deep as the one we followed, and 
discharge at various heights above the river” (a, p. 79).  Gilbert’s 
figure of this canyon has become well known from being copied on the 
binding of Leconte’s “ Elements of Geology,” as if in witness of the effi- 
ciency of erosive processes ; but it may be noted that a plain of dennu- 
dation, truncating the edges of upturned strata, is a much more impressive 
though less outspoken witness to this conclusion. 
THe GEOLOGICAL SECTION IN THE Canyon Watt. — The excavation 
of the Grand canyon is properly regarded as a colossal work. Standing 
on the southern rim, the view of the chasm is overwhelming; yet the 
prospect includes four other records of erosion, and suggests two more 
still, in comparison with any one of which the excavation of the canyon 
is but a small matter. This has all been pointed out by Powell and 
others ; but it deserves repeated statement. 
The geological section exposed in the northern side of the canyon in 
the Kaibab, as seen from any of the promontories in the neighborhood of 
Cameron and Berry’s or Hance’s hotels, includes the fundamental crystal- 
lines, the inclined strata of the Grand canyon series (Algonkian), twelve 
thousand feet thick, and the palzeozoic series, over four thousand feet thick. 
