7tf EXPLORING EXPEDITION FROM SANTA Ft; 



a greal imaginary chain, whirl) was assigned ail inordinate extent and a trend 

 altogether hypothetical and abnormal. It is to be hoped that one result of our 

 expedition will be to bring something like order out of the confusion of ideas which 

 has prevailed in regard to the intricate mountain ranges of this region. As has been 

 before intimated, these ranges, though numerous, exhibit no exceptional features, and 

 are comparatively simple and harmonious in structure and trend; while it is true that 

 the great mountain belt north of the San, Juan River, with its higher chains, their thou- 

 sand interlocking spurs and narrow valleys, form a labyrinth whose? extent and' intri- 

 cacy will at present defy all attempts at detailed topographical analysis. It is equally 

 true that a general topographical character has been given to all of this region by a 

 comparatively few lines of lofty summits, which have nearly a north and south trend, 

 and seem to form an integral portion of the Pockv Mountain system. This great truth 

 may he learned at a glance by the drainage of this country; this all Hows through 

 streams which have approximately a, north and south direction. On the south, the 

 tributaries of the San Juan, the Navajo, the Blanco, the Upper San Juan, the Picdra, 

 the Pinos, the Florido, the Animas, the La Plata, and the MancOS, all flow southward, 

 and most of them issue from the north and south valleys, lying between the parallel 

 ranges to which I have so frequently referred. On the north side of this mountain-belt 

 similar topographical features present themselves. The tributaries of Grand River, 

 which sweep tin; hases of the northern extremities of these ranges, almost without 

 exception issue from valleys which have approximately a north and south direction; 

 hence, it is plainly apparent that one greal fundamental idea pervades the topography 

 of all this region, and that one great force has given shape to all its principal topo- 

 graphical features. 



.Most of the prominent ranges visible from our route have received from the Indians 

 and Mexicans distinct names, by which they are well known to those; who know the 

 country; for example, the chain north of the? Laguna, of which the; southern extremity 

 is drained l>v the Ohama and Rio Navajo, is called the Sierra del Rio Navajo or the 

 Sierra del Xavajo. From between the spurs of this sierra flows the Rito Blanco (Little 



White River), so called from the milky color given to its waters by tlu; Cretaceous 

 shales. From the valley separating the tipper part of this sierra from the Sierra San 



Juan, which does not extend so far south, issues that branch of the San Juan River 

 which retains its name. West of the San Juan Mountains, as we shall see as we pro- 

 gress with OUT geological narrative, the Rio delos Pinos issues from the valley between 

 the Sierra San Juan and the Sierra de ios Pinos; "beyond the Sierra de los Pinos 

 the great valley of the Animas; then the Sierra de la Plata, west and north of which 

 lies the Sierra San Miguel; west and south of the latter chain, the broad expanse of the 

 Colorado Plateau. From this sketch, it will be seen that the greal east and west chains 

 of the Sierra San Juan and Sierra de la Plata, which form so conspicuous features on 

 some of OUT maps, have really no existence, and need therefore no longer vex us as 

 incongruous elements in the orology of our country. 



Like the Santa Fe .Mountains, the Sierra San Juan terminates abruptly south- 

 ward, standing out as a bold headland on the margin of the sea-like plateau. The 

 altitude of its highest summits must be nearly 13,000 feet, as snow lies on them in 



