Note 83 — Chapter VI · THE PLAIN OF THE PAMPAS

Certain features of the hydrographic network clearly have the character of having been superimposed: that is to say, the path of the watercourses has been bequeathed to the actual plain by former erosion-surfaces, which have now disappeared, on which the valleys were originally imposed. That is why in the district of the confluence of the Colorado and the Chadi-Leuvu the valleys pass from Pampean deposits to the crystalline sierras, which were at one time entirely covered with water.