270 BUEEAU OF AMERICAN ETHNOLOGY [bull. 52 



The Rio Salado flows in a meandering channel whose character 

 is shown in the photograph (pi. 25). It is peculiar that the river is 

 like a canal, flowing between steep banks, apparently in perfect equi- 

 hbrium and of uniform regimen. The fall seems to be just sufficient 

 to carry off the waters and the sediment which they bring, and there 

 is no evidence of flood waters, sufficient at least to rise above the 

 banks and spread out on the flood plain. Thus the level grassy 

 surface of the pampas stretches straight to the river bank without 

 elevation or depression, and one does not reahze that the river is there 

 until one is upon it. 



Within sight of the station General Belgrano, but at a distance of 

 an hour and a half's drive from it, there is a low ridge which is a 

 conspicuous feature in the level plain. From near the surface of this 

 ridge, on the estancia "La Georgina" belonging to Senor George M. 

 Mendez, Doctor Ameghino found a human skeleton. Guided by his 

 directions, the writer visited the spot on June 23, 1910, for the pur- 

 pose of studying the topograpliic and geologic relations in which the 

 skeleton had been found. 



The central features of the locahty are the ridge and the hollow 

 known as that of the Arroyo Siasgo, which winds along its southern 

 base. The writer approached the ridge from the east and followed 

 its northern base for about 3 km. It is not continuous, but consists 

 of three or more long low elevations. The northern slope is gentle, 

 sinking imperceptibly into the perfectly level plain, which stretches 

 away to the northward. At the estancia "La Georgina" the ridge 

 was crossed at a point where it sinks away to the westward, and the 

 southern slope and the Arroyo Siasgo came into view (pi. 26). The 

 southern slope of the ridge is relatively steep. At the top it shows 

 effects of wind erosion and portions of the grass-covered margin have 

 slid down. Toward the bottom it is gentler and passes into the 

 hollow by a curve similar to that of the lower part of an earthy talus. 

 It is covered with vegetation. Near the top the sod is broken by 

 sliding and undercut by the wind. The Arroyo Siasgo is a winding 

 hollow. Water from a recent rain was standing in pools in the lowest 

 parts of it, but it was all overgrown with herbage. The width of the 

 hollow is somewhat indefinite, since it has no well-defined southern 

 bank. From the lowest portions, which are below the general level 

 of the plain, there is a very gentle rise southward for perhaps a kilo- 

 meter before the uniform altitude of the plain all about is reached. 



The hollow and the hill have a definite relation to each other. The 

 hollow is a winding depression; the hill is a winding ridge which 

 closely follows its northern side. According to an estimate based 

 on observation in driving past and in walking over the hill and through 

 the hollow, the volume of the one above the plain is about equal to 

 that of the other below the plain. The position of the hill is to 



