Pee Ahi ee ANS RED SBE DS CAND TEER AG ie 
THERE is not another formation in the entire Rocky Moun- 
tain region as conspicuous or as universal as the Red Beds. Go 
where you will, you find the strata of this dark red formation 
very near the base of the mountain ranges, often formiag con- 
spicuous hogbacks, and furnishing examples of wind erosion 
seldom if ever equaled. No formation in the arid west is so 
welcome to a geologist as he enters a field for the first time; for 
its lithological characteristics are so marked and uniform that 
it forms a horizon indicator that immediately furnishes a work- 
ing basis. 
From the days of the pioneer geologists in the Rocky Moun- 
tains, the majority have assigned the Red Beds to the Triassic. 
A few have been quite guarded in their opinions, and have given 
the matter unusual attention; but it has been the consensus of 
opinion that the formation was barren of fossils, and, since it 
was usually found above Coal- measures and below Jurassic, that 
it must be Triassic. 
Hayden was the first geologist to publish anything in refer- 
ence to the Laramie Plains. Unfortunately his observations 
were of the roughest reconnaissance type. In referring to the 
geology of the Laramie Mountains he says :? 
East of the Big Laramie River, and along the western slope of the Lara- 
mie range, the entire series of unchanged rocks are visible, inclining at mod- 
erate angles, from the mountain sides. On the west side of this range the 
slope is more gentle, and the Carboniferous, Triassic, Jurassic, and Creta- 
ceous beds present their upturned edges clearly to the scrutiny of the geolo- 
gist. 
The nucleus is red syenite for the most part, while from the margins 
In referring to the structure of the same region, in the same 
report, he says :3 
* Published by permission of the director of the United States Geological Survey. 
* HAYDEN, Second Annual Report, p. 89. 3 Jbid., p. 82. 
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