552 L. Lesquereux—Lignitic formations of the Rocky Mountains. 
LeConte,* I consider it as Eocene. And if, as I remarked above, 
the Dakota roup does not extend t o New Mexico, this ex- 
plains the absence of the sicasieae: shells of the Middle 
and Upper rp and the position of Tertiary lignite in 
proximity to the 
On the third sarah of Dr. LeConte, I have nothing to 
remark but this: that the shells reported from Dr. Owen’s and 
Prof. Cox’s exploration were found, as positively recorded 
in the note and the section of Prof. aaae at the base of the 
he poser of Cretaceous shells half a mile north of a 
bed of coal, by my friend Capt. Be Pibsotids does not indicate 
that the strata- “beanie shear overlie the coal. At Prhaeere the 
And, for the Bribes of Gen. Pierce concerning a bed of coal 
on the Platte, with Cretaceous fossils on both sides, as nobody, 
not even Dr. LeConte, under the guidance of Gen. Pierce, has 
found this coal, it has to be erased from the page of reliable 
documents. ~All along the base of the mountains, especially 
from Platte Cafion to Coal Creek, the Tertiary and ‘Cretaceous 
strata are much disturbed, often folded and crushed vertically 
against each other, and their relative position is very difficult 
to ascertain. 
What is left then of the repeated assertion that fossil shells 
and bones of Cretaceous ne have been whet in the Lignitic 
— of Color ado ? A single, badly-preserved specimen of 
covery, for I well know that a number of Cretaceous anima 
remains are found in Wyoming over beds of lignite. But I 
* Dr. Hayden found at the same — iy axe balsamoides, Ficus tiliefolia, 
m Mississippiense, Magnolia, etc. — Eocene plants. 
fo bespehe Cox, in letter, April 6th, 18 
| Since writing this, a most valuable my detailed letter, received from Capt. 
Berthoud, settles this question, as as follows: “ That if Mr. Stevenson observ 
8, Baculites, tes, ete., in superposition i gn ig vice it was — a foe 
i. e., that sh gni 
up that with the moat seams near it, it was thrown over the perpendicular. 
That as remarked to Prof. LeConte, r “foead’ ws the locality named a coal bed 
as i 
wins & dip could not be t was badly cut by the drainage of a small 
bluffs north west, I found several s seemed to 
a clay bed in the blufis; but whether the coal was as supe the 
clay or the clay to the coal, I could not say. ” is letter and 
: evide: f th Tertiary » of the Colorado 
ala 
