130 HATCHER — OLIGOCENE AND MIOCENE DEPOSITS. [Aprils, 



line of precipices forming the plateau may be traced from Villa 

 Maria to near Miranda. 



'' On the Dourados side the case is different. Long bays of the 

 flood-plain run back among the hills and often contain lakes of 

 considerable size. The Dourados chain itself is narrow and on the 

 other side are more floodlands, the region called ''Ceo e Terra " by 

 the Brazilians. The Brazilian-Bolivian Boundary Commission tried 

 to pass over this land but had to turn back. 



" The Paraguayan flood-plains are connected with the Ceo e Terra 

 region by several strips which cut the Dourados chain. Hence the 

 Dourados are like a chain of islands. 



" A narrow neck of rocky but low land divides the Paraguayan 

 flood- plain from similar plains in the Guapore ; those on the 

 Guapore are continuous to the junction of the Madeira where 

 there are rapids ; beyond that a flood-plain extends to the Amazon, 

 broadening out. The Amazonian plain is connected in much the 

 same way with the Orinoco. The Orinoco, Amazon and Paraguay 

 are like each other in their flood-plains, which broaden out as we 

 ascend the rivers. 



"■ Except for a single break at the Fecho dos Morros (which may 

 not be a continuous wall) a great plain stretches from Villa Maria 

 to Rosario and beyond. The Xaraes, Chaco and Pampa differ 

 only in their relations to the river floods. The pampas are above 

 reach of the floods \ the Chaco plains are also above the floods, but 

 so low that the water drains off slowly ; the Xaraes are covered at 

 high water. The Paraguay and its continuation, the Parana, cut 

 deeper and deeper into the plains as they flow southward, 

 hence the difl'erences in physical features, which are more apparent 

 than real." 



From the above description it will be seen that the flood-plain 

 of the Paraguay at the mouth of the Sao Louren^o has a width of 

 one hundred and fifty miles and that it broadens as we ascend the 

 river. It is a well-known fact, as stated by Mr. Smith, that the 

 flood-plains of the upper Paraguay, Amazon and Orinoco Rivers 

 are confluent, and that a vast region about the headwaters of those 

 streams possesses physical conditions in every way similar to those 

 just described as obtaining over the flood-plains of the upper 

 Paraguay. Here it appears to the present writer we have a region 

 of equal or greater area than that occupied by the Oligocene and 

 Miocene deposits of our Western plains, with all the physical 



