[174] 296 
tion relatively to so formations farther east, I am inclined to refer it to the 
cretaceous formatio 
Longitude 98°, lasieiidde 39°; Smoky Hill river.—The specimens from this. 
locality are numbered 26, 29, 31, 33, and 88. They all bear a similar char- 
acter, and the fossils are alike in each. The rock is an impure limestone, 
pretty compact, varying in color pars dull yellowish to ashy brown, and 
abounding in shells of a species of Inoceramus. (See description.)  - 
This rock probably belongs,to the cretaceous formation; the lower part 
of which has been — by Dr. Morton as extending into Louisiana, 
Arkansas, and Missou 
Although the apechitbas from this locality beara more close resemblance: 
to the upper part of the formation, I do not feel justified in referring them 
to any other period. This formation evidently underlies large tracts of 
country, and extends far towards the base of the Rocky mountains. 
- Longitude 105°, latitude 39°.—The Aygo sin from this locality are a 
somewhat porous, light-colored limestone, tough and fine grained. ~ 
or two fragments of fossils from this locality still indicate the cretaceous 
period; but the absence of any perfect specimens must deter a positive 
opinion upon the precise age of the formation. One specimen, however, 
from its form, markings, and fibrous structure, I have referred to the genus 
inoceramus. 
It is'evident, from the facts presented, that little of important geological © 
change i is observed in travelling over this distance of 7 degrees of longi- 
tude. But at what depths beneath the surface the country is underlaid by - 
this formation, I have no data for deciding. Its impurtance, however, must 
not-be over! ~ A calcareous formation of this extent is of the greatest 
advantage to a country; and the eco oe eee hence afforded in 
a nd the uses of a life, cannot be overstated. 
- The whole formation of this region is phdbatty, ites some variations, 
an extetsion of that which prevails through Louisiana, Arkansas, and 
jor 
‘The: puta at the locality last mentioned are represented as being verti- 
eal, #standing against the eastern slope of the Rocky mountains, immediately 
below: Pike’s Peak. 
Longitude 106°, ane 41°.—At this point, although oy one degree 
_ ‘west of the last-named specimens, we find a total change in the geology 
: the region. The epeounsas are of : “ Sete Sieg erate; showing a 
tendency to decomposition; and, from the inform sae me ying the 
'  same,this rock overlies a mass of naan air ath i mote af vanced stages 
. oF positi specimens present nothing peculiar in their ap- 
2 pearance; and the e only apparent difference Berwenial Y these and the ordinary 
Ps d feldspathic granites of more eastern localities, is their finer grain and 
ong Neds: 107°, latitude 413°—The specimens from this locality are of 
ystalline canevst thie granite, of a -flesh-red color, apparently not acted on 
3 the: ‘weather, and presenting the common appearance of this kind of 
granite in other localities. 
» No. 95, “above: the third bed of coal, in the lower eo — fork of the - 
Platte river,” is a siliceous clay slate, having : a saline 
_ me aia wee latitude 413°; Nos. 99 and fone: 99 is-a fine- 
grained, soft reillacesasli limestone, of a light ash’ eolor, evidently a modern: 
q cams Sait i froabidiiiibaenee ot fossils, it would be unsatisfactory to - 
