320 Reviews—Dutton’s Grand Canon, Colorado. 
of verdure, denudation progresses chiefly by the recession of the 
cliffs. It is Captain Dutton’s belief that the whole thickness 
denuded off the district during Tertiary time was on an average 
9000 feet. 
It does not strike us that the amount of denudation here is more 
surprising than in many other regions. It is the abnormal forms 
which it has impressed upon the surface, and the strange scenery 
that results, which renders this country so peculiar. These forms 
the author attributes to the nearly level position of the beds, their 
great homogeneity in horizontal, and heterogeneity in vertical exten- 
sion; and these acted on by the meteorological influences of an arid 
climate. Dr. Geikie attributes much of the denudation to wind, and 
the descriptions certainly favour that view. 
Along a narrow strip at the bottom of the gorge the river has cut 
into a series of rocks older than the Carboniferous, and unconform- 
able to it. These are believed to be Silurian and Archzean. 
A system of great faults maintaining an average direction at right 
angles to the dip traverses the region. A further peculiarity of this 
peculiar country is that these faults give rise to more cliffs. The 
altitude of the ground on the’ upthrow side exceeds that on the 
downthrow by the amount of throw of the fault. Commonly we 
may stand over a fault of thousands of feet without any surface in- 
dications of its presence. Here, however, the faults have formed 
lofty cliffs, which have, comparatively, not receded very far since 
they were uplifted. The obvious conclusion is that the country has 
never been submerged since the disturbances took place. 
As an effect of these faults, and of a great roll, or monocline, 
which is evidently a modification of the same kind of action, the 
country, through which the Colorado has dug its carion, is divided 
into subordinate plateaux of different altitudes. These have each 
their special features. The first and second from the west, the 
Sheavwits and Uinkaret, are marked by their basaltic outflows ; those 
of the latter being much more recent than of the former. The 
third is the Kanab, a desert region. The fourth is the Kaibab, the 
most lofty of all, elevated into the clouds, and watered by their 
kindly distillations. This is the paradise of the province, and the 
subject of enthusiastic encomiums with the author. 
Captain Dutton has bestowed a great deal of pains, and of logical 
reasoning, upon the drainage problems. He has succeeded in show- 
ing how the present rivers, fed as they are from a distance, have held 
the same courses from the conclusion of Hocene time. He shows 
when they worked rapidly, and when more slowly, in abrading their 
beds; and points out how the present colossal features of the Canon 
were produced. He takes care to remove from the mind an im- 
pression, which certainly needed to be removed, that the Grand Cation 
is a deep and dismal chasm, shut out from the shining of the sun. It 
is nothing of the sort. It consists first of a valley ten or more miles 
wide, with precipitous sides a mile deep, having its bottom trenched 
with an inner gorge 1000 feet deeper still, and perhaps twice that 
width. The sides of the upper valley are carved into immense 
