Marcu 14, 1884.] 
GEOLOGY OF THE GRAND CANON. 
Tertiary history of the Grand Cajiion district. By 
CLARENCE E. Dutton. (Monographs U.S. geo- 
logical survey, ii.) Washington, Government 
printing-office, 1882. 264p., 42 pl. 4°. Atlas, 
aa sh. £°. 
Turis work is the second in numerical order, 
though the first in date of publication, of the 
monographs of the U. S. geological survey. 
It is not a geological report in the generally 
accepted sense of the term, but deals strictly 
with the physical problems displayed by the 
Grand Canon district, and, as its title indi- 
cates, principally with that part of its history 
embraced in the tertiary period, of which the 
distinguishing feature in this region is denuda- 
tion on a stupendous scale. 
The first geological exploration of the Grand 
Caiion of the Colorado is due to Major Powell ; 
and for several years his name was closely asso- 
ciated with the progress of discovery in this 
field. Finding himself, however, unable to 
continue the work, it was delegated to Capt. 
Dutton, who had already become familiar with 
some parts of the district ; and the present mon- 
ograph is the best possible evidence that Major 
Powell has found no unworthy successor in his 
investigations. 
Capt. Dutton writes as one in love with his 
subject; and it would indeed be surprising if 
any geologist who has had the privilege of 
studying this region were otherwise than en- 
thusiastic in regard to it. A large part of the 
western territory is such that the geologist who 
runs may read; that even from the windows 
of the railway more facts may be gleaned in a 
day’s journey than could be certainly arrived 
at by months of study in a wooded country, 
or one mantled by the northern drift. In ad- 
dition to these advantages, common to vast 
tracts, the Grand Canon presents the most 
striking river-section in America, and perhaps 
inthe world. In such a field a more complete 
knowledge of the problem is possible, and a 
closer and more logical method in its treatment 
admissible, than elsewhere, — circumstances 
fully taken advantage of in the present report. 
The high plateaus of southern Utah descend 
to the south in a succession of gigantic ter- 
races, composed in succession of the eocene, 
cretaceous, triassic, and Permian formations, 
till the summit of the carboniferous is eventu- 
ally reached. This forms a wide platform, with 
some approach to regularity of surface, but 
drops at length in an escarpment of great cliffs 
to the desert and sierra regions of the farther 
south and west. The terrace country has a 
SCIENCE. 
327 
width of from thirty to forty miles, with a 
length of about one hundred, and forms, as it 
were, a giant stairway, leading down from the 
high plateaus, with an elevation of over ten 
thousand feet, to the carboniferous platform, 
five thousand feet or more lower. ‘The whole 
rock series has a preponderant northward dip of 
an extremely regular character, which seldom 
exceeds two degrees, and is generally less than 
one degree, inamount. The carboniferous sur- 
face presents a corresponding light slope from 
south to north ; and the strata are traversed by a 
series of faults and congenetic monoclinal flex- 
ures, running in north and south courses, but 
showing a convexity toward the west. ‘These 
define the several minor plateaus which diver- 
sify the surface ; but the region, as a whole, is 
characterized by the proximate horizontality 
and undisturbed condition of its rocks, and is 
in marked contrast to the turmoil of flexed 
beds found in the adjacent sierra country. 
Across the carboniferous platform, in a gen- 
eral south-westward course, the great canon 
has been cut, — a vast chasm, with atotal length 
of about two hundred miles, a depth of from five 
thousand to six thousand feet, and a width of 
from five to twelve miles. 
The history of the canon district, from the 
later paleozoic to the present day, is naturally 
divided into two widely contrasted periods ; the 
first extending from early carboniferous time 
into the eocene, having been one of steady, 
conformable deposition, bed succeeding bed, 
till a thickness of about fourteen thousand feet 
was accumulated. To this succeeded a period 
of continuous erosion, during which an average 
thickness of ten thousand feet of the strata was 
removed from a large part of the surface. 
Though rather heterogeneous in character 
as compared among themselves, the beds of the 
Grand Cafion region in general closely resem- 
ble those representing the same horizons in 
other parts of the west. The archaean and 
other basal rocks, not throwing any light in the 
physical problem proposed in the monograph, 
are merely mentioned. The carboniferous, 
broadly viewed, may be characterized as chiefly 
limestone; and the conditions of a somewhat 
deep sea at the time of its formation are im- 
plied. The Permian and triassic are mainly 
represented by sandstones, which frequently 
display cross-bedding, and denote that the 
water at the time of their deposition was con- 
tinuously shallow. In the cretaceous, argilla- 
ceous and marly rocks become more abundant ; 
and the occurrence of coals and carbonaceous 
layers throughout, shows that portions of the 
region became land-surfaces from time to time. 
