OF NORTH AMERICA. 
13 
lower is formed of thick beds of whitish-gray 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 excep- 
tion of the amaranth yellow color, which 1 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 con- 
sistency, 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 whole trees, 
are often met with. On the western declivity of the Sierra Madre, between Zuni and the Rio Co- 
lorado Chiqiiito, 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 2). 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 
Calamodendron. 
1 connect with this Third Division the Red Sandstone, containing footprints and fishes, of the 
Connecticut valley, as well as the coal-basin of Chesterfield county, in Virginia, and the Red Sand- 
stone in North Carolina, contrary to the opinion of Messrs. Rogers and Hall, who call it Liassic, 
and even Oolitic^'). Its equivalent in Europe is, without doubt, the Marnes Irisies of France, the 
Keuper of Germany, and the Variegated Marls of England. 
*) The cellular tissue has almost entirely disappeared, and the wood is replaced by a very com- 
pact flintstone of an extremely brilliant color, presenting fieautiful specimens for the exercise of the la- 
pidary's art. The Indians of these regions use them for ornaments , and also to make points for their 
arrows. 
2) In the same locality , at the point where the expedition crossed the Lithodendron Creek , near 
our camp N° 77 (latitude 34°, 57', 56"; longitude west from Greenwich 109°, 47', 27".), I found in this 
gray reddish Sandstone several valves of a fossil shell , that I refer without doubt to the Genus Cardinia, 
though they are not in a state of sufficient preservation for specific description. The genus Cardinia, 
in Europe, is confined to the Carboniferous, New Red Sandstone (Permian and Trias), and Jurassic 
epochs. 
3) The first examination (1834) of the Richmond coal-field, led Richard C. Taylor to refer it to the 
regular coal-mea.sures of the Carboniferous period. In 1843, William B. Rogers, after a more careful sur- 
vey and basing his opinions upon several species of fossil plants resembling more or less some Jurassic 
plants found in Yorkshire and Scotland, referred without hesitation « the coal of Eastern Virginia to a place 
in the Oolite System on the same general parallel with the carbonaceous beds of Whitby and Brora — that is. 
in the lower part of Ike Oolite groups. (See: Reports of the .issociation of American Geologists; page 300; 
Boston, 184X) 
