Situation of Zones without Eain, and of Deserts. 371 



are elevated chains presenting bold and sharp forms, whose 

 summits have an altitude of about 6300 feet, offers, as the 

 most characteristic feature, the mountainous band which ex- 

 tends from Rio Janeiro to near Pernambuco. This band rises 

 on the Atlantic coast to a mean height of 3250 feet, and 

 includes the lofty summits of Itacolumi, Itambe, and the 

 Morro ; so that if it constitutes between 23° and 10° S., a 

 barrier analogous to that of the Guianas, it also differs from 

 it in another respect, in that while it does not approach 

 the equator nearer than 10° S., the other terminates at the 

 equator. 



It results, therefore, from the opposite position of these two 

 littoral chains, that the mean axis of the largest of the basins 

 of South America, that alone which traverses almost entirely 

 the continent in a direction parallel to the equator, is, as it 

 were, refoule at 5° of south latitude, and that the breadth of 

 its entrance on the Atlantic side is comprised between 0° and 

 10° south. 



These masses of mountains become lower towards the inte- 

 rior, and lose themselves, the one in the Llanos of the Ornocco, 

 and the other towards the Campos Parieceys, as well as in the 

 vast plains of Moxos and Chiquitos, where it constitutes, in 

 16° and 18° south, a simple threshold, so to speak, upon which 

 we may unite artificially the Paraguay to the Amazon by 

 means of the Madera ; just as on the other side in 2° and 3** 

 N., the communication with the Orinocco is effected by nature 

 by means of the Rio Negro, and the Cassiquiare. We have, 

 therefore, a great system of depression, varying, according to 

 Von Humboldt, from 200 to 1100 feet in height, extending 

 from the Cordillera of the coast of the Venezuela to the 

 Straits of Magellan, and forming an area of 456,900 square 

 leagues. It comprehends the Savannahs, the Llanos, the Pam- 

 pas, and the Steppes of the Orinocco, the Amazon, the Plata, 

 and of Patagonia, which preserve, for distances of from twenty 

 to thirty days' journey, an imposing and melancholy unifor- 

 mity ; palms grow at their one extremity, while the ground is 

 frozen at the other ; lastly, from time to time, this monotony is 

 broken by lagoons, by sands, and by the mass of virgin forests, in 

 the midst of which are discovered immense low islands of naked 



