The Saint Paul globe. (St. Paul, Minn.) 1896-1905, 1897-03-07

turned. 1t is thus difficult to know to
what elevations these rocks may have
been thrust up in some places, but a
minimum estimate may be arrived at
by tracing the combinations of the beds
over the less disturbed anticlinalS or
by adding their volume to the eleya-
ton Of the flat-lying ranges of the
Older rocks. About latitude so degrees
it may thus be shown that the base of
the cretaceous must in several places
have considerably exceeded 10000 feet
in altitude, While in MIR. McCOnnelPs
section along Bow pass (51 degrees 10
minutes1 the same horizon
must have been about Is, 900 feet above
sea-level. the beds at this place being
nearly fiat. To ascertain the uplift OF
the the beds which were at sea-leVel
at the close Of the cretaceous, the vol
ume of the cretaCeous strata must,
Of course, be added to such figures as
the above. This was, in the eastern
part of the mountains, at least 1900
feet, and may have been 20,0 600 feet
giving as a minimum estimate
of greatest uplift for the region say
% 900 to 81, 900 feet 1t is prob
ably impossible to ascertain exactly
how long the main uplifting process
continued or to what extent it's effect
was cOunteracted by concurrent 'denu-
dation." This author states it as his
belief. however, that the mountain up
lifting and folding may have continued
through the very long eOcene and mio-
Gene periods, which may be estimated
to have comprised together about nine
tenths Of the tertiary era. During the
early part of the miocene period DR..
Dawson thinks that the Rocky noun
tains adjoining the west side of the
Canadian portion of the great plains
We're "a range comparable to the Hima-
layas in height
The geologic strata of this northern
portion of the plains are the Dakota,
Colorado, Montana, and Laramie for
nations, of late CreJaceouS age, whose
deposition took place during the clos
ing part Of the secondary or meSOZoic
era. Southwark, in the United States,
the plains comprise extensive deposits
Of tertiary lacustrine beds. represent
ing the continuation of the brackish
water and finally lacustrfne conditions
which prevailed over large areas of the
plains during the Laramie period; but
in the northern region, crossed by the
Missouri river and extending to the
Peace and Mackenzie rivers, no tertiary
beds are found Since the beginning
of the tertiary era this region has been
a land surface undergoing denudation.
When it's marine and lacustrine de-
positS were first raised to be dry land
they had a mOnotonouSly fiat surface.
A very long cycle of baSe-leveling en-
sued, beginning as soon as this northern
part of the plains was uplifted at the
end of cretaceous time and continuing
nearly or quite to the end of the ter
tiary era. During this time the surface
was gradually lowered by the action
Of rains, rills, rivuletS, creeks, and
rivers, until it was mostly reduced to
a base-leVel of subaerial erosion.
Across an area 700 or 800 miles wide
from east to west on the international
boundary and of much greater extent
from south to north, the processes Of
baSe-leveling were at work through
the vast duration of tertiary time, cut
ting down the plains far below their
original surface. But here and there
isolated areas of hills and even noun
tainS remain, consisting of remnants
of the horizontal cretaceous strata
which elsewhere have suffered erosion.
The most noteworthy eastern high
land area of this kind is the Turtle
mountain, lying in the north edge of
| North Dakota and the south edge of
Manitoba, it's extent on the interna-
tional boundary being about forty
miles, with two-thirds as great width.
This high tract, diversified by many
subordinate hills and short ridges, so
to 800 feet above adjoining depressions,
rises with a massive general form Sug-
costing, as seen from distant points
of view, the rounded back OF a turtle;
but as seen from the south or north,
its many hills and buttes present a
| serrated outline. It's altitude above the
surrounding country is 800 to 500 feet,
the SUBMITS of its highest hills being
about $500 feet above the sea- Beneath
a yenee9ing Of glacial drift, which fs I'm