56 
GEOLOGY 
form and at first view reminded me of the Jura mountains between Aarau and Soleure , as seen at some 
distance from the plains of Switzerland. 
Camp N° 9. — Anton Chico is situated on the New Red Sandstone rocks, in which are found nu- 
merous beds of gypsum and dolomite at some distance in following the river towards Cuesta. Our road 
rises and we pass over strata of white and yellow Jurassic sandstone before reaching the Canon Blanco, 
where the bottom of the narrow valley is formed by the upper part of the Keuper. We encamped at 
the top of a perpendicular cliff, eight hundred feet above the Rio Pecos and the village of Cuesta. The 
bottom of the valley or canon in which the Rio Pecos flows is formed by rocks belonging to the New 
Red Sandstone, and two thirds of the cliff, including the top, are Jurassic rocks. 
Camp N° 10. — We cross entirely the Canon Blanco; the formation is constantly the same as on 
the previous day’s march. 
Camp N° 11. — I do not find any geological notes in my private journal of this day’s march. 
Camp N° 12. — Near the village of Galisteo is a trap dyke, direction 30° east-east-north and 30° 
west- west-south , cutting through the strata of the New Red Sandstone. A thick alluvium composed of 
angular fragments of granite, sicnite and quartz of moderate size, covers the whole country between 
camps N? 11 and 12. — N° 12 is placed in the midst of volcanic cones, called Cerrito, that surround 
us on all sides. 
Camp N° 13. — From Cerrito to the Pueblo de San Domingo we pass by the village of Cieneguilla. 
It is situated at the entrance of a deep canon at the junction of volcanic rocks with porphyric dyke and 
the strata of the New Red Sandstone. The upper part of the canon is formed by basaltic lava, while 
the lower is a volcanic conglomerate superposed upon New Red Sandstone. In the direction of Pena 
Blanca we met with a very thick formation of white friable sandstone , the equivalent of the White Chalk 
of Europe. Our camp N° 13 is near the Rio Grande del Norte on the Quarternary formation. 
Camp N° 14. — From Santo Domingo to Sandia our road lay all the time on the Quarternary rocks, 
except at the Pueblo of San Felipe, where the valley is contracted and the volcanic lava covers the 
mesa on each side of the river. 
Camp N° 15. — From Sandia to Albuquerque, Quarternary rocks with sand-dunes in the process 
of formation near Alameda. 
Camp N° 16. — From Albuquerque to Tigeras the first twelve miles are on the alluvium of the Rio 
del Norte valley, then the road enters the Canon of San Antonio and is on granite for three miles, until 
near a very narrow pass , where the granite is replaced by a sort of serpentine trap. These last rocks 
appear to be metamorphic and are only two hundred feet thick; masses of limestone strata of the age 
of the Mountain Limestone are superposed upon them. Fossils are common, and I found in this Lower 
Carboniferous limestone the following species: Proditctus semi-reliculatus , P. Cora, P. Flemingii, P. punc- 
tatus, P. pustulosm , P. pyxidiformis ; Terebratula plano-sulcata , T. sublilita; Spirifer linealus, Sp. strialus, 
Sp. Rocky— montani ; Amplexus coralloides and Zaphrentis Stansburyi. The strata are upheaved, dipping to 
the east, at an angle of 35 degrees. The limestone is bluish-gray, sometimes black, very hard and 
about four hundred feet thick. 
Camp N° 17. — For one mile from camp N° 16 to the village of Tigeras the road is on the Car- 
boniferous rocks; the New Red Sandstone begins at the village, and in the ascent to San Antonio and 
Antonito we pass through all the different divisions: the red sandstone, dolomite, gypsum and varie- 
gated marls, exactly the same rocks we met with for so long a distance in the Prairies from Delaware 
mount to Anton Chico. 
Camp N° 18, 19, 20, 21, 22, 23, 24, 25. — As 1 have given the most important details of this 
part of the survey in the note on pages 20 and 21 of the present volume I will add nothing more here, 
more especially as the geology of this part of the country is quite complicated and would require vol- 
umes to do justice to it. 
Camp N° 26. — From N° 25 to 26 Rio del Norte alluvium. 
