G6 EXPLORING EXPEDITION FROM SANTA FE 



preceding chapter; mountains somewhat vaguely designated on different maps as 

 Sierras San Juan, Salnvatcli, &c. By the Mexican mountaineers, all the mountain 

 mass, drained by the western headwaters of the Rio Grande, is known under the name 

 of the Sierra El Wanico. 



On both sides of the valley the Carboniferous strata may be seen exposed in 

 numerous localities, dipping rapidly inward toward the river; resting 'conformably upon 

 these, the red beds of the Triassic series, here soft, sandy, and extensively eroded. Over 

 a large part of the valley surface the drift from the adjacent mountains is spread so 

 thickly that the rocky substrata are wholly concealed. It is possible, therefore, that 

 in some localities the Cretaceous rocks hold their relative position there, as elsewhere, 

 upon the Trias. I cannot say, however, that I have ever seen the Cretaceous strata 

 in the immediate valley of the Rio Grande, except on the slopes of the Organ Mount- 

 ains, above El Paso. 



Between Santa F<5 and the month of the Chama the country is much broken and 

 generally sterile. Rounded gravel hills, dotted with scrubby trees of cedar and pin on, 

 and eroded buttes of pale red, pulverulent sandstone, everywhere meet the eye and 

 give character to the scenery. Among these, wind threads of fertility, following the 

 courses of the streams, marked by lines of cottonwood, by meadows of coarse grass, 

 and, in some localities, by fields of grain. On the west side of the river the scenery is 

 bolder, the surface more broken and unproductive; the character which it exhibits hav- 

 ing been given, for the most, part, by floods of lava poured out from the Valles, now 

 remaining in sheets and masses of black and ragged trap. Reaching up toward the 

 mountains are many valleys of erosion in which the parti-colored strata of the Triassic 

 series are visible, even at a distance of many miles. 



VALLEY OF THE COAMA. 



The course of the Chama, as before stated, lies in a natural gap in the mountains 

 bordering the Rio Grande on the west. Below Abiquiu its valley has essentially the 

 character of that of the Rio Grande, of which it may be indeed said to form a part. 

 On the southwest it is bounded by the slopes and the trap mesas of the Valles, and on 

 the north by the gentler declivities of the mountains of Conejos. At Abiquiu Ihesc 

 boundaries closely approach each other, and the river seems to have burst through the 

 low axis of elevation connecting the Valles with the northern mountains. On the 

 south side the trap mesas come flush up to the stream, and, just below the village, 

 overhang it in a cliff 800 feet in height. On the north side are high and broken 

 hills of erupted rock, formed by a series of dikes crossing each other at different, 

 angles; the principal one having a trend nearly north and south, from which diverge 

 one with a northeast and southwest trend, and another running a little north of west 

 by south of east. These minor dikes are also much broken and forked. The gate 

 through which the river passes this axis of elevation is exceedingly bold and 

 picturesque; its beauty being enhanced by a high and ragged bntte of rock, wjiich 

 stands disconnected from either side, partially blocking up the gap. It should also be 

 mentioned that a similar line of displacement crosses the river below Abiquiu, in the 

 form of a sharp interrupted ridge, known throughout that region as the Cuchillo or 



