xlviu • INTRODUCTION. 



Further east, to tlie Eio Grande and beyond itj tliey ar^ 

 dislocated, and finally lose their distinctiye character 



of 



j 



o 



"In the interval between Fort Defiance and the Eio Grande 

 lises a great volcanic mountain^ Monnt Taylor (San Mateo), 



+ + 



which, like that of San Francisco, has burst through the 

 sedimentary strata^ and poured over them floods of lava, 

 which are as fresh as though ejected but yesterday. 



" The highest of the table-lands which we passed over was 

 formed of Lower Cretaceous strata ; and yet another must be 

 added to the series before my description of them will be 

 complete. 



'^On our route across the continent, we passed someAvliat 

 south of the centre of what we may, perhaps, properly call tlie | 

 basin of the Upper Colorado, and did not, therefore, mount 

 quite to the summit of its geological series. Going 'north 

 from the Moquis villages on the Lower Cretaceous mesa, our ^ 

 progress was arrested by a want of water, the surface being 



everywhere cut by deep canons, by which it is drained ta 



excess, every rain-drop which falls finding its way immediately^ 

 into the bottom of these rai^ines, where it. is hurried off to the 

 far deeper canons of the Colorado and its larger tribiitnncs- 

 Before we tui'ned hack, however, we had approached ncanj'j 

 to the base of a wall, rising ahrnptl j from the m csa in whicfl j 

 we stood to the height of more than 1,000 feet. This Tvall 

 was as white as chalk, and reflected the sunlight like a v^^ 

 of snow. It is evidently the edge of another and a hig^^ 

 platean, and apparently reaches to the Eio Colorado, where i 

 caps the high mesa, forming part of the stupendous m^i^"^' ; 

 faces presented towards the south and west, which were dis- 

 tinctly visible when we had receded from them to the distant 

 of one hundred miles. 



