GEOLOGY OF NORTH AMERICA. 
55 
a second gigantic step or grade, called by the Mexicans Monte Revuelto. This augmentation of the 
Llano and the worn fossils found in the creeks, show that the Jurassic rocks have become more de- 
veloped and contain fossils. 
Camp N° 4. — From N° 3 to N° 4 the road continues on the red and variegated sandy marl of the 
Upper Keuper; but on the south are seen the magnificent cliffs and ravines of Monte Revuelto, and the 
Big Tucumcari, and on the north the two isolated pie-formed mountains known by the name of Little 
Tucumcari. These cliffs and ravines are almost perpendicular, generally denuded and without vege- 
tation, and show all the strata. 
From the base half way up, the formation is the red marl of the Upper Keuper, then come white 
and yellow sandstones, with some beds of limestone of the same colors, and a band of blue clay near 
the summit. We found in the beds of Fossil and Tucumcari creeks several specimens of Gryphwa di- 
latata var. Tucumcarii.' 
Monte Revuelto, the Big and Little Tucumcari are certainly most important points for the geology 
of this region, and 1 have no doubt that a careful examination of them will be productive of useful re- 
sults; the rapidity of our march did not permit me to visit either, although we passed within half a mile 
of 'the base of each one of them. 
Camp N° 5. — From N° 4 to N° 5 the road is on the red and variegated marl of the Upper Keu- 
per. until within two miles of camp N° 5 Laguna Colorada, where we found the red and gray sand- 
stone of the lower part of the Keuper. Plaza Larga and Pyramid Mount are situated between these two 
camps, and as I have described my excursion to Pyramid Mount in the notes of the first chapter, see 
pages 17, 18 and 19 of the present volume, I will not add any thing on that subject. 
Camp N° 6. — The water of the Laguna Colorada flow's over strata of red sandy marl and soft red 
sandstone , which impart to it so much rod color that it resembles chocolate more than water. Our road 
is constantly on the Keuper, and the Llano Estacado two or three miles to the south is no longer ca|)ped 
bv Jurassic rocks as w'as the case before we reached the Laguna Colorada, but is formed by the red 
sandstone of the Keuper. All the different creeks we pass contain red and brackish water. 
Camp N° 7. — From N° 6 to N° 7 the road is on the I'cd sandstone of the lower part of the Keu- 
per, but we see at some distance to the North several hills of the same form as Little Tucumcari, which 
appear to be capped by Jurassic rocks. These i,soiated mountains are called by the Mexicans los 
Esteros. 
Camp N° 8. — From N'^ 7 to N° 8 the road is (|uite hilly, and we begin to enter the true Rocky 
mountain region , whose summits we see for the first time three miles west of Hurrah creek. The elong- 
ated hill separating Hurrah creek from the Rio Gallinas is capped by a whitish gray limestone similar 
to the Jurassic limestone of the Llano Estacado. In the valley of the Rio Gallinas we meet with an Al- 
luvium coming from the Rocky mountains, composed of pebbles of mean size, of rose granite, sienite, 
quartz, and more commonly of green trap or basalt. During our whole journey from Napoleon to the 
Rio Gallinas I was often struck by the entire absence of alluvium; from time to time you sec a few 
inches of sandy alluvium with small quartz pebbles generally of the size of a robin’s egg , never larger 
than the fist; and yet you see all round you evidence that the country has been denuded and washed 
away on an immense scale. This absence of alluvium in the Prairies near the 35"’ degree of latitude 
is very striking as contrasted with the immense quantity of alluvium that covers the northern region, as 
in New England, Canada, New York, Michigan, Wisconsin, etc. 
Between the valleys of the Rio Gallinas and of the Rio Pecos our road was on the alluvimn or on 
the Keuper, but as it is evident that the alluvium rests on the strata of the New Red Sandstone, I have 
colored the whole road as New Red on the map. On our right we see a table land , called Man of war 
Butte, which appears to be capped by Jurassic rocks. 
The Rocky mountains when first seen are at a distance of forty miles, and do not give the idea of 
majesty and grandeur yon expect from such celebrated mountains; they have nothing alpine in their 
