LOWER CRETACEOUS STRATA. 85 
Feet. 
& Green shales. 6 ee eT OS Se Pe IE ee Pee ee Pe 28 
9. Coarse yellow or white sandstones {0020554 OF SOOT ORS PPR at Pe 80 
10. Green shales with bands of sandstone; in some localities all soft greenish yellow 
BANCSEOHER 8). ee Ee AP Pa BE FT 0 See Fee 60 
11. Coarse light yellow or whitish massive sandstone.--. +... .+++ esse cece cues -» 120 
12. Green shales with bands of ferruginous sandy limestone and beds of lignite.” “ti 
this group, at Oraylee and Camp 96, are Pinna? lingula (n. sp.) and Gryphaea 
Pitchert ; and over the lignite beds are impressions of leaves of Platanus, Alnus 
Wise” &c., and fossil ferns of the genus Sphenopteris .--- +++ .+:+ cece vevees 90 
Green, blue, and gray argillaceous shales, with bands of brown or yellow silicious 
limestone, containing Ammonites percarinatus, Inoceramus Crispii? and Gryphaea 
— 
Petchert, Var. navia Pe TES TET SUF BOF Ce ate 160 
14. Coarse yellowish sandstone, precisely like Nos. 9 and 11, (base of Cretaceous forma- 
tion ?) 0 Oe a Witte ee CAR MET CW ee Gwiere See VN T 6 +e ee 64 6 oc bee Ce Ce eb Sete CUE Vee tee 95 
15. Lignite, (Jurassic?) better than that above, to base.-+--.--+.+ esse eeee cee wens + 
Of these strata the lower two have been already noticed in the description of the section 
exposed at Camp 92. 
It will be seen that there is great lithological similarity among all the strata of this mesa, 
while they are strikingly different from those of the one below it. 
I have no hesitation in including all above the lower lignite bed in one geological group; and 
this is proved by its fossils to be a subdivision of the great Cretaceous formation, probably rep- 
resenting the lower third of that series. 
The palzontological evidence of the age of these rocks is quite conclusive, and of unusual 
value, as it fixes the place in the geological scale of a well-marked formation in New Mexico, 
and one which has been the subject of considerable discussion. In the second member of the 
Cretaceous portion of the section, counting from the base upward, are contained fossils which 
are characteristic of the Cretaceous formation in Texas and Nebraska. These are Jnoceramus 
Crispii and Gryphaea Pitcheri—well known Cretaceous fossils, common in Texas and the Indian 
Territory—and in greater numbers specimens of an ammonite, (A. percarinatus,) highly charac- 
teristic of Nos. 1 and 2 of Meek and Hayden’s section of the Cretaceous rocks on the upper 
Missouri. 
The vegetable impressions contained in No. 12 indicate a more highly organized flora than 
any which occupied the earth’s surface previous to the Cretaceous period, and afford conclusive 
evidence that the strata containing them are not, as has been supposed, of Jurassic age. U 
to the present time no angiosperm dicotyledonous plants have been found in strata older than 
the Chalk; and yet (though making my collections under the most unfavorable circumstances) 
I here procured representatives of several genera belonging to this class. 
These plants afford another link connecting these strata with those of the upper Missouri. 
Their general character is quite similar to that of the exceedingly interesting group of plants 
obtained by Dr. Hayden from the Lower Cretaceous sandstones of Kansas and Nebraska, several 
of the genera and at least one species being common to the two localities. A somewhat similar 
flora has been discovered by Mr. Harper in Mississippi, Professor Tuomey in Alabama, and 
Professor Cook in New Jersey, in strata of the same age. 
There is no doubt of the parallelism of this group of sandstones with those of the base of 
Meek and Hayden’s Cretaceous section. It is true that in Kansas and Nebraska they are more 
often red than yellow or white, yet in some localities they exhibit the same lithological charac- 
ters as in New Mexico. Going from Santa Fé to Fort Leavenworth, I noticed a progressive 
change from yellow to a reddish color in these sandstones, which for several hundred eens were 
almost continually in sight, and of which the continuity is uninterrupted. 
