262 Gravel-Terraces of Guasco. paet n. 



grand terraces, running at corresponding heights on 

 both sides of the broad valley, are more conspicuous 

 than the three best developed ones at Coquimbo. They 

 give to the landscape the most singular and formal 

 aspect; and when the clouds hung low, hiding the 

 neighbouring mountains, the valley resembled in the 

 most striking manner that of Santa Cruz. The whole 

 thickness of these terraces or plains seems composed of 

 gravel, rather firmly aggregated together, with occasional 

 parting seams of clay : the pebbles on the upper plain 

 are often white-washed with an albuminous substance, 

 as in Patagonia. Near the coast I observed many sea- 

 shells on the lower plains. At Freyrina (twelve miles 

 up the valley), there are six terraces beside the bottom- 

 surface of the valley : the two lower ones are here only 

 from 200 to 300 yards in width, but higher up the 

 valley they expand into plains : the third terrace is 

 generally narrow : the fourth I saw only in one place, 

 but there it was distinct for the length of a mile : the 

 fifth is very broad : the sixth is the summit-plain, 

 which expands inland into a great basin. Not 

 having a barometer with me, I did not ascertain the 

 height of these plains, but they appeared consider- 

 ably higher than those at Coquimbo. Their width 

 varies much, sometimes being very broad, and some- 

 times contracting into mere fringes of separate fiat- 

 topped projections, and then quite disappearing : at 

 the one spot, where the fourth terrace was visible, the 

 whole six terraces were cut off for a short space by one 

 single bold escarpment. Near Ballenar (thirty-seven 

 miles from the mouth of the river), the valley between 

 the summit-edges of the highest escarpment is several 

 miles in width, and the five terraces on both sides are 

 broadly developed : the highest cannot be less than 

 600 feet above the bed of the river, which itself must, 



