402 PASSAGE OF CORDILLERA. March, 1835. 



second day's journey, we found only one little pool. The 

 water flowing from the mountains is small in quantity 

 and soon becomes absorbed by the dry and porous soil; 

 so that, although we travelled at the distance of only ten or 

 fifteen miles from the outer range, we did not cross a single 

 stream. In many parts the ground was incrusted with a 

 saline efflorescence ; hence we had the same salt-loving 

 plants, common near Bahia Blanca. The landscape has one 

 character from the Strait of Magellan along the whole eastern 

 coast of Patagonia to the Rio Colorado ; and it appears that 

 the same kind of country extends northerly in a sweeping 

 line as far as San Luis, and perhaps even further. To the 

 eastward of this line, lies the basin of the comparatively damp 

 and green plains of Buenos Ayres. The former country, 

 including the sterile traversia of Mendoza and Patagonia, 

 consists of a bed of shingle, worn smooth, and accumulated 

 by the waves of a former sea ; while the formation of the 

 Pampas (plains covered by thistles, clover, and grass) is due 

 to the estuary mud of the Plata, deposited under a difierent 

 condition of circumstances. 



After our two days' tedious journey, it was refreshing to 

 see in the distance the rows of poplars and willows growing 

 around the village and river of Luxan. Shortly before we 

 arrived at this place, we observed to the southward a ragged 

 cloud of a dark reddish-brown colour. For some time, we 

 had no doubt but that it was thick smoke proceeding from 

 some great fire on the plains. Soon afterwards we found it 

 was a pest of locusts.* The insects overtook us, as they 

 were travelling northward, by the aid of a light breeze, at the 

 rate, I should suppose, of ten or fifteen miles an hour. The 

 main body filled the air from a height of twenty feet, to that, 

 as it appeared, of two or three thousand above the ground. 

 The noise of their approach was that of astrongbreezef pass- 



• The species is identical with, or resembles most closely, the famous 

 Gryllus migratorius of eastern countries. 



f " And the sound of their wings was as the sound of chariots of many 

 horses running to battle." — Revelat. ix. 9. 



