GUIANA HIGHLANDS 133 



Guiana Highlands. These constitute a northern out- 

 lier of the Brazilian highlands, of which they reproduce 

 the main features : successions of broad terraces broken 

 by sunk valleys and rising in step?, with remnants of 

 mesas forming ridges or plateaus. Some of the mesas 

 reach elevations of from 6,000 to 11,000 feet. 



The Guiana tableland is isolated and open both to 

 Atlantic and equatorial winds; it has therefore more 

 rain and is cooler than the surrounding plains. The 

 northern and eastern lower terraces are clad with 

 dense rain-forests, while the valleys share the savana 

 character of the lowlands, of which they are the con- 

 tinuation. On the slopes, half-way up, rise open woods 

 of evergreen trees with a hard, leathery foliage, recalling 

 our ilexes and laurels. To these, with increasing eleva- 

 tion and rainfall, denser forests of a warm temperate 

 type succeed, to give way in turn, farther up, to an open 

 park landscape of fresh green swards and clumps of 

 low, stunted trees. The higher tables are treeless steppes. 

 In respect of structure and vegetation, the Guiana table- 

 lands recall the Uganda plateau, with the advantage of 

 a more abundant rainfall. 



A belt of rolling savanas fringes the tableland on 

 the south and west, and separates it from the Amazon 

 selva. The aspect of those ' campos ' differs somewhat 

 from that of the Orinoco llanos. They are rolling wolds, 

 treeless, and covered with large tufts of tall grass, 

 panicum and paspalum, which are sometimes broad- 

 leaved and four to six feet high. These grasses become 

 shorter on the back of the ridges, and are abundantly 

 interspersed with bulbous and tuberous plants, and 

 thorny bushes. The troughs, dales, and hollows, often 

 marshy or damp, form islands or belts of thin low woods, 

 where palms are a conspicuous feature, the round patches 



