Grant County herald. [volume] (Lancaster, Wis.) 1850-1968, 1885-07-09
GEOLOGY OF THE WEST.

GEOLOGY OF THE WEST.
Capt. Clarence f. Dutton, of the ord
nance department of the army. who,
says telegram to the New York
Times, has been engaged for ten years
IN the study of the geology of the great
plateau region OF the west, started last
week for California, under instructions
from Maj. Parnell, director of the geo.
logical survey, to make a study of the
| geological phenomena presented by the
Cascade Mountains, the greatest vol
canic range upon the globe Before
his departure Capt. Dutton finished the
manuscript of his contribution to the
next annual publication of the geolog-
cal survey. The paper is entitled.
"Alount Taylor and the Zuni Plateau"
but, although it treats in detail of only
two features Of the plateau region, the
conclusions which these are made to
illustrate embody in the part the result
OF years of study, extending over very
wide area.
! Of the history of the plateau region
| prior to the carboniferouS time he saws:
Little is known to biologists. In the
latter part of this period the western
| portion OF the United States was ma
rine area. If any land existed it was
of small extent. The strata deposited
at the time disclose no plants or land
animals among their fossils, while ma
rine mollusca are abundant. The wa
tiers were neither very deep nor very
shallow. In the Immediately succeed
ing geological periods, during the dep
| osition OF the permian and jura trias
strata, 4 curious alienation of land
and sea is found to have taken place,
! the level surface of the region oscillat-
| ing from little above TO little below
sea level. During its seasons of eleya-
1 ton 1t supported exuberant forests.
| through which roamed Il highly-varied
reptiliaa fauna. The region appears to
have subsidized about rs fast as the sedi-
ments were accumulated. thus presery-
| ing the surface at nearly constant
| level, and it is surmised that the oscil-
lations may have been due to variations
in the absolute position of the sea
level.
Whatever may be the explanation, it
certainly is 4 most extraordinary fact
| that between 5000 and 1000 feet of
strata were accumulated upon an area
OF over go 900 square miles, and vet the
! surface OF deposition was maintained
throughout at approximately the same
level. During the cretaccous time the
| alterations from blooming forests to
! shallow seas continued, but the fossil
romans of this time are of greater va
ricty, and are found in greater abund-
ance. Early in this period the mollus-
can fossils are of the marine type, but
] in 10 20 Il
brackish-water type. Whence. the
author asks, came the materials which
| constitute the mesozoic strata of the
west, covering nearly !. 100000 square
miles to the average depth of more
than $500 feet The great basin which
has been enormously ravaged over an
area of 200,0 900 square miles by evasive
forces furnished a portion of the mate
rial, and possibly small land areas in-
| sular in character existed further
south.
| But it is not credible that these
sources furnished one-half the materials
of the mesozoic strata. The fact is qcn-
eral that these strata grow thinner
from west to east, indicating n western
| origin, and the author concludes that
they came from some great continental
| area, with 4 coast line many hundred
miles long, with numerous rivers dis
charging sand and sl,i all along its
course. Passing on TO tertiary time,
the fossils of { early coccne strata are
found to be still of the brackish type.
but are replaced by frcsh-water forms
n little higher up. Thus. il is inferred
that the complete isolation of the pla-
teau province was accomplished at the
beginning OF the tertiary time, and its
area became, in great part at least, Il
vast inland lake with an outlet
In the eoccnc age the great mountain
platforms of the Wasa;ch. Wintas, and
Rockies were upheayed and underwent
rapid denudations. The resulting sedi-
nients were carried down into the lake,
where they were deposited. sometimes
to the .ieIhn 0. live thousand feet. With
the progress of roccnc lime the lake of
the plateau region gradually vanished,
| The southern part being the first to dry
| up, and with its disappearance ended
the Lore, period of deposition. The ac-
cumulated strata reached the thickness
! of 10, 900 feet in the western part, and
not less than 10. 800 in the east. Atm
| time could the surface of deposition
have been very far from sea level. The
| progress of tertiary time witnessed the
slow elevation of the entire mountain
and plateau region of tine west, and
along with the dcnudation OF the cOun-
| try the author traces the geological
| history Of the region down TO its pres
ent condition, finding evidences of al
ternating periods of moisture and dry
ness, of great and sudden uplifts Of
great areas and of slow and long con-
tinued rising in others, and of the de-
nudasion of immense tracts, and the
cutting of canyons by the waters.
In the study of the Zuni Mountains
| he finds reason for the conclusion that
! the mountains OF the west have not
| been produced by horiz lntal compress
sion, but by the action of some TN
| known forces beneath, which have lift
| ed them up. Upon the extensive pla-
! teau of which Mount Taylor is the CEN
ter he finds ample confirmation of the
theory that the volcanic cap which once
covered so large portion of the region
and which still tops so many extensive
mesas, had its origin not in discharges
from immense volcanic mountains like
| Mount Taylor itself, but through in
Vulnerable vents through the sediment
airy strata. These evidences consist
largely in the numerous huge "neeks"
of lava, from the vicinity of which the
sedimentary deposits have been erodcd.
| These necks are the contents of once
existing tunnels, through which the
molten lava was forced 10 spread IL
self in thin cap over the level country
above They explain the existence Of
the lava-beds at the present time SO far
distant from the nearest volcanic
mountain as to preclude the SUPPOSE
ton That the two ever had any connec-
| ton.
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