PHYSICAL GEOGRAPHY. li 



water in their formation.- The oi:)posite sides of the 



_^ epest chasm showed perfect correspondence of stratification, 



""informing to the general dip, and nowhere was there displace- 



ent ; the bottom rock, so often diy and bare, was, perhaps, 



T.eeply eroded, ^bnt continuous from side to side, a portion of 



3 yet undivided series lying below. The mesa walls should 



|c je included in the same category with those of the canons — 



metimeSj indeed^ they arc but cailons, miles in breadth. 

 '' The origin of the series of escarpments which are met 

 i^h in crossing the table-lands from west to east is, I think; 

 ejiendent upon yery general, but yet appreciable causes, to 

 'hich I can here, however, but briefly allude. 

 ^"^ "From the Cerbas Mountains to the base of the high 

 esa,* the strata composing the high table-lands have a 

 >rth-easterly dip of about 100 feet to the mile. There they 

 j i'rise, but soon dip again into the valley of the Little Colorado, 

 lOfW'heir strike being nearly at right angles with the com-se of 

 oicivfhe great draining stream, the Colorado. By a glance at the 

 lib' Qap, it will be seen that the watershed, made up by the San 

 lif '•'rancisco group, the Mogollon, and the spurs of the Eocky 



4 



tin? 'fountains, which throws the water into the Colorado over the 

 ' ; '^able-lands from the south, south-east, and east, forms a semi- 

 :cle imperfectly parallel with the course of the Colorado, 



Qto which the drainage from the different parts of this semi- 

 dii^ii-cle falls nearly at right angles. The &ow of waters from 

 , .v'tie mountains has therefore been here, as elsewhere along the 

 *trike of the strata, north and north-west from the San 

 ' "'"'rancisco and Mogollon mountains on the western side of the 

 J#*a.sin. The lc"-itimato and inevitable effect of this combina- 

 f ; •• ion of causes has been to erode the softer down to the Jiarder 



trata, forming broad valleys, bounded on the west by the 



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true 



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