CHAPTER IV. 
GEOLOGY OF NEW MEXICO. 
GEOLOGICAL MAP OF NEW MEXICO. — PLATE VIIL 
The geological map of a portion of New Mexico, represented plate VIII, was drawn with the 
help of my private journal, several letters written to geological friends during my stay at Albu- 
querque, Santa Fe and the Pueblo of Zuni, and some notes marked by me on several maps of 
New Mexico in my possession while travelling in that country. I have marked by a broken line the 
uncertain limits of several geological formations; having followed one line of march, I could not 
fix the limits of the different rocks on the north and south of this line. The track of the survey 
is marked by a dot and line, and the positions of the dilferent camping grounds are marked by 
numbers. 
I have not divided the Carboniferous rocks into two parts, as is usually done; both on account 
of the small scale of the map, and also because the Coal-measures are represented only by thin strata 
of black argillaceous schist. The Mountain Limestone is much more developed than the Coal-measures, 
and forms the principal part of the Rocky mountain Carboniferous rocks. This map must be re- 
garded as a first essay upon a country about which the geological notions have hitherto been very 
vague , and I publish it only as a first attempt upon a terra incognita. 
Camp N’ 1. Rocky Dell creek. — The camp is situated on a whitish-gray sandstone, of very mas- 
sive stratification, with intercalation of red-colored schistose beds. These rocks are easily disintegrated 
and denuded by atmospheric action and running water, and in the ravine of Rooky Dell creek present 
several caves with Indian hieroglyphics sculptured on the walls, and on the plateau where the camp was 
placed there are many grotesque forms produced by these causes, such as gigantic pot-holes, sugar 
loaves, enormous cakes etc. This sandstone forms the lower part of the Keuper of New .Mexico. Two 
miles west of the camp is an isolated mountain , whose abrupts are formed of the upper part of the Keu- 
per, consisting of red and variegated sandy marl, two hundred feet thick. The summit is capped by 
beds of a compact gray limestone very analogous to the Low'er Oolite — Calcaire do la citadelle do 
Besangon — of the Jura mountains. This Jurassic limestone is fifteen feet thick and contains no fossils. 
Camp N° 2. — From N° 1 to N° 2 the road is constantly on the red and variegated sandy marl of 
the Upper Keuper and skirts the northern foot of the Llano Estacado. 
Camp N° 3. — From N° 2 to N° 3 red sandy marl as before. In the beds of several creeks run- 
ning from the Llano Estacado are seen several specimens of the Gryphcea dilatata var. Tucumcarii much 
broken and worn away. From camp N° 3 the immense table-land of the Llano Estacado is seen to have 
