chap. vin. Valley of Santa Cruz. 205 



illustrative; for during our hurried ascent it was im- 

 possible to measure all the plains at any one place. 



No. 20. 



North, and South Section across the Terraces bounding the Valley of 

 the River Santa Cruz, high up its course. 



A south. A north. 



~"\ B 3. B n. 



> \ Cs. Ds. E. Dn. C n. 



y 



1,122 ft. 869 ft. 639 ft. Bed of 639 ft. 869 ft. 1,122 ft. 



river. 



The height of each terrace above the level of the river, is shown by the number 

 under it Vertical scale ■£$ of inch to a 100 feet ; but terrace E being only 

 twenty feet above the river, has necessarily been raised. The horizontal dis- 

 tances much contracted ; the distance from the edge of A n. to A s. being on an 

 average from seven to ten miles. 



At a point nearly midway between the Cordillera and 

 the Atlantic, I found the plain (A north) 1,122 feet 

 above the river ; all the lower plains on this side were 

 here united into one great broken cliff: at a point 

 sixteen miles lower down the stream, I found by 

 measurement and estimation that B (n) was 869 above 

 the river : very near to where A (n) was measured, 

 C (??,) was 639 above the same level : the terrace D (n) 

 was nowhere measured : the lowest E (n) was in many 

 places about twenty feet above the river. These plains 

 or terraces were best developed where the valley was 

 widest; the whole five, like gigantic steps, occurred 

 together only at a few points. The lower terraces are 

 less continuous than the higher ones, and appear to be 

 entirely lost in the upper third of the valley. Terrace 

 C (s), however, was traced continuously for a great 

 distance. The terrace B (?i), at a point of fifty-five 

 miles from the mouth of the river, was four miles in 

 width ; higher up the valley this terrace (or at least 

 the second highest one, for I could not always trace it 

 continuously) was about eight miles wide. This second 



