242 PATAGONIAN EXPEDITIONS: GEOGRAPHY. 



Chico, of nearly ten miles, though at the mouth of the river it contracts 

 again to a narrow passage of only a mile or so in width. 



The Rio Chico of the Santa Cms. — This river discharges into the 

 same inlet as that by which the Santa Cruz empties its waters into the 

 Atlantic. It is, in fact, the north fork of the latter, or, as its name implies, 

 the Little Santa Cruz. It is no mean stream and only second in impor- 

 tance to the Santa Cruz among the rivers of this region. Rising in the 

 Andes in the vicinity of the forty-eighth parallel, it is made up of a 

 number of tributaries, including the Belgrano, which unite at the base of 

 the mountains. Then, taking a southeasterly course, it flows for nearly two 

 hundred miles through a deep valley, which, for a considerable distance, 

 has the appearance of a rugged, basalt-capped canon, before receiving its 

 only other important tributary. Here, at a distance of only fifty miles 

 from its mouth, it receives the Chalia, or Sheuen, from the west. This 

 small tributary, which may be classed among the iutermitteut rivers, rises 

 in the foothills just east of Lake Viedma and flows through a deep valley 

 extending almost due east to that of the Rio Chico. 



Although the Rio Chico flows continuously throughout its whole course 

 and during the entire year, the volume of its waters is scarcely sufficient 

 to keep pace with the elevation that is going on along the region to the 

 eastward and, throughout the last one hundred and twenty-five miles of 

 its course, it has for some time been largely engaged in silting up its 

 channel. The water of the Rio Chico, through most of the year, is 

 derived almost entirely from the melting of snow and ice in the Andes 

 and from the daily precipitation which takes place in the region imme- 

 diately about its headwaters. Except for a comparatively short season in 

 the spring, it derives little or almost no water from the plains through 

 which it flows, save where there are important springs. As would be 

 expected with a river fed by glaciers or melting snow, the volume of 

 water in this river is greatest in that season which is warmest and dryest 

 on the plains through which it flows, and least in winter. This fact will 

 eventually prove to be of great value, when the waters of this stream shall 

 be utilized in irrigating its, for the most part, very fertile valley. 



TJie Valley of the San Julian. — A little south of the forty-ninth par- 

 allel there is an important inlet from the Atlantic, forming the excellent 

 harbor of San Julian. From this inlet there extends inland a deep valley, 

 known locally as the valley of the San Julian. This valley extends westward 



