RESUME. 
167 
much resembling the Pinites fleurotii of Dr. Mougeot, which is found in the New Red sandstone 
of the Val d’Ajol iu the Vosges; and this establishes a connexion between the New Red of France 
and that of America. 
The third division, or upper group of the Trias, is subdivided again into two parts. The 
lower is formed of thick beds of whitish-grey sandstone, often rose-colored, and even red; and 
the upper consists of beds of sandy calcareous clay, of very brilliant colors—violet, red, yellow 
and white—in a word, of variegated marls. This upper portion presents a striking resemblance, 
as to the rocks, with the Marnes irisees of France, or the variegated marls of England. With 
the exception of the amaranth yellow color, which I have never seen in Europe, I could have 
imagined myself transported to some points in the Jura or the Vosges. These rocks having 
very little consistency, have been carried away almost everywhere by denudations. It is only 
where they are capped by the Jurassic strata that they can be observed. The sandstone of this 
third division is very much developed, with rather an indistinct and very massive stratification. 
Its thickness is one thousand feet, while the variegated marls are only four or five hundred feet 
thick—making a whole of fifteen hundred feet for the upper group of Trias. Upon our route 
this sandstone forms the summits of the table-lands or mesas which extend on each bank of the 
Canadian river, from Antelope Hills to the Llano Estacado; then it forms the bottom of the 
valley from Rocky Dell creek and the Plaza Larga to Anton Chico and the Canon Blanco. In 
this group of Triassic rocks, numerous remains of petrified wood, and even of whole trees, are 
often met with. 
On the western declivity of the Sierra Madre, between Zuni and the Rio Colorado Chiquito, 
there is really a petrified forest of trees thirty and forty feet long, divided into fragments from 
six to ten feet in length, with a diameter of three or four feet, some being still upright enclosed 
in the sandstone. These trees and remains of petrified wood belong nearly all to the family of 
the conifers, and some to that of the ferns with arborescent stems, and to the Calamodenclron. 
I connect with this third division the red sandstones of the Connecticut valley, containing 
foot-prints and fishes, as well as the coal-basin of Chesterfield county, in Virginia, and the red 
sandstone in North Carolina, contrary to the opinion of Messrs. Rogers and Hall, who call it 
Liasic, and even Oolitic. Its equivalent in Europe is, without doubt, the Marnes irisees of 
France, the Keuper of Germany, and the variegated marls of England. 
The easy decomposition of the sandstone of this third group has given it all sorts of curious 
forms, which have been compared to ruined temples, natural fortifications, natural mounds, or 
to the forms of gigantic statues, rivals of those of Ivarnac and Nineveh. The celebrated Chim¬ 
ney Rock, on the route to Fort Laramie, is entirely of this formation. 
The strata of American Trias comprise valuable rocks for building a railroad. There are 
found in abundance sandstone for embankments and bridges ; dolomite, which produces an 
excellent hydraulic lime ; gypsum in incalculable quantities, for exportation ; and, finally, salt. 
I have mentioned two points between Topofki creek and Anton Chico where the Triassic 
rocks are covered by more modern formations. The first of these points is upon one of the trib¬ 
utaries of the Washita river, near our Camp No. 31, where, upon the heights, are found the 
remains of beds of a limestone filled with shells, which I connect with the neoeomien of Europe ; 
or, in other words, with the lower division of the cretaceous rocks. This limestone is only five 
feet thick ; it is of a whitish-grey color, containing an immense quantity of Ostracea, which I 
consider (provisionally) as the Exogyra ponderosa , l Roemer ; having the closest analogy with 
the Exogyra of the neoeomien of the environs of Neuchatel. As it is the first time the neoeomien 
has been recognised in North America, where, until now, only the green-sand and chalk-marl, 
or lower chalk, have been found, I will add that these strata are much more developed at Fort 
Washita, where Dr. G. C. Shumard has made a large collection of fossils, such as Pecten quinque 
costatus, Panopea, Toxaster complanatus , and another species of Toxaster , all fossils or genera 
Mr. Marcou subsequently determined this fossil to be Gryphcea Pitcheri, Morton.—W. P. B. 
