312 PATAGONIA 



sources well out on the plains ; so that, were former boundary- 

 treaties interpreted literally, much territory supposed to be of 

 considerable value mineralogically and extensive tracts of rich 

 grazing lands, all now held by Argentina, would revert to Chile. 

 Not only has there never been any attempt at a topographic 

 surve}^ of the country, but throughout vast areas over the plains 

 region of central Patagonia the watercourses as located on all 

 the government and current charts are merely conjectural, while 

 in the region between Lake San Martin and the territory of 

 Neuquen no authentic map showing tbe locations of the princi- 

 pal streams flowing toward either the Atlantic or the Pacific has 

 ever been attempted. 



That part of this region which was visited and traversed by 

 the writer and his assistant, Mr 0. A. Peterson, during recent 

 explorations in behalf of Princeton University and the Bureau 

 of American Ethnology, and especially noticed in this paper, lies 

 between the headwaters of Rio Chico and Rio Santa Cruz and 

 the Strait of Magellan. The principal overland route Avill be 

 found located on the map. From different points along this 

 route shorter excursions were made in all directions. 



The plains region of Patagonia may be considered as consist- 

 ing of a series of benches or steps which appear as successive 

 elevations on the surface as one proceeds from the Atlantic coast 

 overland toward the Cordilleras. The precipitous bluffs of the 

 coast, rising in places to a height of nearly five hundred feet, 

 form the first step in the series, and from this the succeeding 

 benches gradually increase in elevation until along the base of 

 the mountains an altitude, according to Darwin, of 3,000 feet is 

 attained. The escarpments constituting the limits of each of 

 these succeeding benches form irregular but somewhat parallel 

 lines, which conform not only to the general direction of the 

 present coast-line, but also to the courses of the great transverse 

 valleys at the bottom of which flow the larger rivers of eastern 

 Patagonia. This series of benches or steps may be seen not only 

 as one proceeds from the coast toward the interior of Patagonia? 

 but also on either the one or the other side, sometimes on both, 

 of all the greater watercourses of this region distant from the 

 coast and near the mountains. They doubtless represent suc- 

 ceeding bluffs formed along the coast, and mark successive stages 

 in the final elevation of this region which took place toward the 

 close of the Pliocene period. The occurrence of this series of 

 benches along the sides of the river valleys of this region is 



