54 RIO COLORADO. [CHAP. iv. 



extended by his arms and legs horizontally, and there left to stretch for 

 several hours. The idea is evidently taken from the usual method of 

 drying hides. My interview passed away without a smile, and I 

 obtained a passport and order for the government post-horses, and this 

 he gave me in the most obliging and ready manner. 



In the morning we started for Bahia Blanca, which we reached in two 

 days. Leaving the regular encampment, we passed by the toldos of 

 the Indians. These are round like ovens, and covered with hides ; by 

 the mouth of each, a tapering chuzo was stuck in the ground. The 

 toldos were divided into separate groups, which belonged to the 

 different caciques' tribes, and the groups were again divided into smaller 

 ones, according to the relationship of the owners. For several miles we 

 travelled along the valley of the Colorado. The alluvial plains on the 

 side appeared fertile, and it is supposed that they are well adapted to 

 th2 growth of corn. Turning northward from the river, we soon entered 

 on a country differing from the plains south of the river. The land 

 still continued dry and sterile ; but it supported many different kinds of 

 plants, and the grass, though brown and withered, was more abundant, 

 as the thorny bushes were less so. These latter in a short space 

 entirely disappeared, and the plains were left without a thicket to cover 

 then- nakedness. This change in the vegetation marks the commence- 

 ment of the grand calcareo argillaceous deposit, which forms the wide 

 extent of the Pampas, and covers the granitic rocks of Banda Oriental. 

 From the Strait of Magellan to the Colorado, a distance of about eight 

 hundred miles, the face of the country is everywhere composed of 

 shingle ; the pebbles are chiefly of porphyry, and probably owe their 

 origin to the rocks of the Cordillera. North of the Colorado this bed 

 thins out, and the pebbles become exceedingly small, and here the 

 characteristic vegetation of Patagonia ceases. 



Having ridden about twenty-five miles, we came to a broad belt of 

 sand-dunes, which stretches, as far as the eye can reach, to the east and 

 west. The sand-hillocks resting on the clay allow small pools of water 

 to collect, and thus afford in this dry country an invaluable supply of 

 fresh water. The great advantage arising from depressions and eleva- 

 tions of the soil is not often brought home to the mind. The two 

 miserable springs in the long passage between the Rio Negro and 

 Colorado were caused by trifling inequalities in the* plain ; without 

 them not a drop of water would have been found. The belt of sand- 

 dunes is about eight miles wide ; at some former period, it probably 

 formed the margin of a grand estuary, where the Colorado now flows. 

 In this district, where absolute proofs of the recent elevation of the land 

 occur, such speculations can hardly be neglected by any one, although 

 merely considering the physical geography of the country. Having 

 crossed the sandy tract, we arrived in the evening at one of the post- 

 houses ; and, as the fresh horses were grazing at a distance, we 

 determined to pass the night there. 



The house was situated at the base of a ridge, between one and two 

 hundred feet high a most remarkable feature in this country. This 

 posta was commanded by a negro lieutenant, born in Africa; to hi* 



