TO JUNCTION OF GRAND AND GREEN RIVERS. 83 



( i r a i >r r km v. 



(;K()L(m;\ OF THE SAGE-PLAIN AND VALLEY OF THE UPPER COLO- 

 RADO. 



General features of the northern portion of thk Colorado Basin— Aspects and 



STRUCTURE OF THE SAGE-PLAIN— MESA VERDE— ENORMOUS DENUDATION OF THE COLO- 

 RADO Plateau— Crossing the Sage plain— Rio de u>s mangos— Rio Dolores— Section 

 of Loweb Cretaceous rocks— Ruins on the Dolores— Sierra San Miguel— Surou- 

 m:a— Tir.Ki.-A Blanca— Guajelotes— Canon Pintado— Triassio rocks— Saurian bones 

 —La Tenejal— Eroded buttes— Casa Colorado— Ojo Verde— Sierra La Sal— Excur- 

 sion to Grand IIiver— Canon Colorado— Plateau bordering thk Colorado Kiykk- 

 Rroded. monuments— Labyrinth Canon— Ruined buildings— Summit of the Carbon- 

 iferous formation— Section of Triassio rooks— Kemarkable country about the 



.UNCTION OFGRAND AND GREEN KlVERS— SINGULAR ERODED BUTTES AND PIHNACLES— 



Networkof canons— Canon of Grand Uiver— Section of Carboniferous strata- 

 Transverse SECTION OF TDK COLORADO VALLEY— RETURN TO SAGE-PLAIN— JOURNEY 

 SOUTHWARD to THE San Juan— Sierra Abajo. 



Between the Riode la Plata and the Rio de los Mancos we skirted the base of the 

 extreme southern poinl df the Sierra do la Plata. These mountains terminate south- 

 ward in a long Blope, which falls down to a level of about 7,500 loot above the son, 

 forming :l plateau which extends southward to the San Juan,the Mesa Verde, to which 

 1 shall soon have occasion again to refer. This mesa terniinates on the west by an 

 abrupt nearly vertical precipice from L,20 i to 1,600 feet in -height Between the mesa 

 :111(l tll( . mountains is a natural pass or puerta, through which the Spanish trail leads 

 where it crosses the divide. On the west this puerta opens to the right andlett; 

 feounded n the north by the retreating southwesterly slopes oi the Sierra de la 1 ata 

 on the south by the wail-like edges of the Mesa Verde. As we stood on its threshold 

 we boked far out over a greal plain, to the eve as limitless as the sea; the monotonous 

 outline of its surface varied only by two or three small island-hke mounteins,so distant 

 as scarcelv to rise above the horizon line. Here we were to leave the lofty sierras oi 

 ;, lt : Rocky Mountain system, which had so long looked down on our camps and mashes 

 fche picturesque seenerv of the loot-hills, their llowerv valleys and sparkling Steams, 



L fateful shade of iheir noble forests, and take our weary way across the arid ex- 



„; f le«>reat western plateau; a n-^ou wla.s, drearv na-notonv.s ; adv broken . 

 iul haL, where alone the weary traveler Ends shelter Inunthe bui-mn, hea „ 

 Indies, sun and where he seeks, t. ften in vain, a coohng draught that hal] 



