DISTRIBUTION OF BOULDER STONES. 345 



zuela, although the immense plains were immediately 

 bordered to the south by a group of mountains entirely 

 granitic *, and which presents, in its broken and almost 

 columnar peaks, traces of the most violent action -f-. 

 Towards the north, the granitic chain of the Silla of Ca- 

 racas and of Portocabello is separated from the Llanos, 

 by a range of mountains which are schistose between 

 Villa de Cura and Parapara, and calcareous between the 

 Bergantin and Caripe. I was equally struck with the 

 same absence of blocks upon the banks of the Amazon. 

 La Condamine had already affirmed, that from the Pon- 

 go of Manseriche to the strait of Pauxis, not the smal- 

 lest stone was to be observed. Now, the basin of the 

 Rio Nigro and of the Amazon is also but a Llano, 

 a plain like those of Venezuela and Buenos Ay res, the 

 difference consisting only in the state of the vegetation. 

 The two Llanos, situated at the northern and southern 

 extremities of South America, are covered with grami- 

 neae ; they are Savannas destitute of trees. The inter- 

 mediate Llano, that of the Amazon, exposed to almost 

 continual equatorial rains, is a thick forest. I do not 

 remember to have heard that the Pampas of Buenos 

 Ayres or the Savannas of the Missouri J and New 

 Mexico contain granitic blocks. The absence of this 

 phenomenon appears general in the new world. It 

 is probably equally so in the Sahara in Africa ; for we 



* The Sierra Parima. 



t T. ii. p. 233, 236, 252, 273, 288, 382, 597, 627, and 633. 

 Are there any blocks in North America to the north of the 

 Great Lakes ? 



