26 BUREAU OF AMERICAN ETHNOLOGY [bum. M 



drop to lower altitudes and finally merge into the general level of the 

 region. 



The western portion of the basin is part of the Jemez plateau, 

 which includes the Jemez mountains and is bounded on the west by 

 the Rio Puerco and on the east by the Rio Grande, extending from 

 the northern line of New Mexico to about west of Santa Fe. The 

 portion of the Jemez plateau lying between the Jemez mountains and 

 the Rio Grande is called the Pajarito plateau. The Rito de los 

 Frijoles is in the southern part of the Pajarito plateau. Approxi- 

 mately parallel canyons extending from east to southeast divide the 

 plateau into a number of mesas, which slope rather gently from the 

 mountains to the rim of the Rio Grande canyon. 



Standing on any high point just west of Santa Fe, one may gain a 

 clear conception of the larger features of the topograpliy — the broad 

 basin lying between two mountain ranges, the country sloping some- 

 what regularly from the bases of the mountains on each side to the 

 river. In traveling over the region these larger features of the land- 

 scape may often seem, to one not thoroughly familiar with them, 

 swallowed up or obscured by the magnitude and abruptness of the 

 topographic forms in the immediate vicinity of the observer, so that 

 the final impression is that of a confused network of deep, narrow 

 lateral canyons and rugged buttes. To understand the region, one 

 must ever keep in mind the idea that here were originally gentle, 

 uniform slopes, which have been deeply gashed by canyons cut by 

 running water. 



In traveling up the valley from Santa Fe to Taos, on the east side 

 of the Rio Grande, Carboniferous formations with low westerly dips 

 are found along the flanks of the mountains, exposed by the wearing 

 away of the overlying "marls". Doubtless the Carboniferous rocks 

 and probably later formations are spread across the valley beneath 

 the mantle of Tertiary sedimentary formations which are usually 

 exposed where not covered by tufa and basalt. It seems probable 

 that the outlines of this valley were established as a synclinal fold 

 long before the nlid-Tertiary deposition period, but the altitude of 

 the mountains then is a matter of conjecture only. The exposed 

 strata show that these Tertiary sediments were deposited in the 

 valley to a depth of 1,200 to 1,500 feet, according to Hay den, but it 

 seenLs likely that he included some Quaternary strata with the 

 Tertiary. "The upper portions are yellow and cream-colored sand- 

 stones, sands, and marls. Lower down are some gray coarse sand 

 beds with layers of sandstone."^ These beds have since been deeply 

 cut by stream erosion, the Rio Grande having excavated a deep 

 valley, including" the great valley of Taos. The formation has been 



1 Hayden, F. V., Geological Report, (,3d Ann.) Prelim. Field Rep. U. S. Oeol. Surv. Colo, and New 

 Mex.for 18r,9, pp. 7-99, 1869; 1st, 2d, and 3d Ann. Reps. V. S. Oeol. Surv. Terr, for 1867, 1868, 1869, pp. 

 109-99, 1873. 



