Ch. X.] PARALLEL ROADS OF COQUIMBO. 131 



rounded blocks. One of these cliffs appears in the hill behind 

 Barios del Pujio, about 700 feet above the level of the sea, and 

 200 above the contiguous valley. Another occurs at Aman- 

 caes, at the height of perhaps 200 feet above the sea, and others 

 at intermediate elevations. 



Parallel roads of Coquimbo. We can hardly doubt that the 

 parallel roads of Coquimbo, in Chili, described by Captain 

 Hall, owe their origin to similar causes. These roads, or shelves, 

 occur in a valley six or seven miles wide, which descends from 

 the Andes to the Pacific. Their general width is from 20 to 

 50 yards, but they are, at some places, half a mile broad. 

 They are so disposed as to present exact counterparts of one 

 another, at the same level, on opposite sides of the valley. 

 There are three distinctly characterized sets, and a lower one 

 which is indistinct when approached, but when viewed from a 

 distance is evidently of the same character with the others. 

 Each resembles a shingle beach, being formed entirely of loose 

 materials, principally water-worn, rounded stones, from the 

 size of a nut to that of a man's head. The stones are prin- 

 cipally granite and gneiss, with masses of schistus, whinstone, 

 and quartz mixed indiscriminately, and all bearing marks of 

 having been worn by attrition under water *. 



The theory proposed by Captain Hall to explain these ap- 

 pearances is the same as that which had been adopted to 

 account for the analogous parallel roads of Glen Roy in Scot- 

 land f. The valley is supposed to have been a lake, the waters 

 of which stood, originally, at the level of the highest road, until 

 a flat beach was produced. A portion of the barrier was then 

 broken down, which allowed the lake to discharge part of its 

 waters into the sea, and, consequently, to fall to the second 

 level ; and so on successively till the whole embankment was 

 washed away, and the valley left as we now see it. 



As I did not feel satisfied with this explanation, I applied to 



* Captain Hail's South America, vol. ii. p. 9. 



f See Sir T. D. Lander, Ed. Roy. Soc. Trans., vol. ix., and Dr. Macculloeh, 

 Guol. Traus., 1st Series, vol. iv. p. 314, 



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