, 1925-07-23
are still preserved, especially on the

are still preserved, especially on the
south.
Public spirited citizens of Casper
have placed a bronz tablet in it's
northern face and erected a granite
monolith, thereby commemorating
these Ayers, pioneers and explorers
Yet none have so far spoken or
written of a most interesting event
inscribed in old independence Rock
in the geologic 49's." Situations
alongside the tablet and monolith
record unmistakable evidence of pre-
Oligocene glaciation. This is an i'm
portant chapter in Wyoming and
also American historical geology, be-
ling the first definite recorded glacia-
ton in North America. Some have
thought there is Permian Glaciation
in the mid continent, but of this there
is a little question as to its validity.
The great ice sheet which came down
into the United States from Canada
was in a much later period-the
P~leistoCene.
Situations are parallel scratches
and grooves cut in bedrock by rocks
carried in the bottom of a glazier, or
scratches in the carried rocks them
selves. The slow moving ice shoves
these included boulders over the bed
rock, and they, acting as tools, scour,
scratch, gouge and smooth the bed
rock. The striae are geologic c~riteria
as certain and sure evidence of trans
pired events as finger prints are in
dices of evidence in criminal proceed
ure.
Striae of the same character can
be seen just at the south end of Path
finder Dam. Doubtless in many other
places the pre-Cambrian granite and
schist of the Sweetwater valley SINH
lar marks can be found il M had the
time TO search for them. For in
stance, a few miles east of ~Independ,
ence Rock, just off the trail the out
crops of black schist, which are like
hugh layers on end, are beveled OFF
nicely and otherwise smoothed and
faceted by the ice.
Viewed as a whole, Independence
Rock is typically ice worm, as shown
by its smoothed surface and rounded
shape. 1t is a first class example OF
a roches mountonnee "a rock sheep,
as the Scandanavians would say
In the right sunlight, by standing a
short distance away from the rock on
the north side, it glistens from the
polishing it has received by the ice.
All the Granite Mountains, which
rise more than 5000 TT. above sea-
level. as we'll as the Rock, have been
overridden by the pre-Oligocene
glacier which dispersed from the high
portions of the Wind River Range
and passed eastward a hundred miles,
or as far at least as Alcova and Bates
Hole, where large erratic igneous
boulders are found scattered beyond
the limits of the White River forma-
ton. The thickness of the glacier
must have been at least 800 feet.
Boulders 20 IT. in greatest dimen-
sion are found on top of Green Noun
tain; also nearly as large one on
Crooks Mountain and Whiskey Peak.
All these mountains have elevations
OF about 5000 TT. These boulders,
heretofore maverick in geologic age,
cap the Wasatch formation of Eocene
age and are now branded past-Eocene
The glacial fill in the new state
highway five miles west of Alcova is
the key which. traced about one mile
southwest toward Pathfinder dam, abb
solutely proves pre-Oligocene glacia-
ton. because this bed of boulder fill
outcrops beneath the White River for
nation of Oligocene age. So the evil
dence up and down the ~Sweetwater
valley shows positively that Central
Wyoming was visited by a large gla-
cier in the mid-Tertiary period.
As far as / am aware, the only
other case of Tertiary glaciation is