ENTRANCE OF THE LLANOS. 103 



south of this place the gneiss is concealed beneath a chap. xv. 

 deposite of serpentine, which, farther south, passes 

 into or alternates with greenstone. This rock is now the Grecustone. 

 principal one, and in the midst of it rise the Morros of 

 San Juan, composed of crystalline limestone of a 

 greenish-gray colour, and containing masses of dark- 

 blue indurated clay. Behind the Morros is another 

 compact limestone containing shells. The valley that 

 descends from San Juan to the Llanos is filled with trap- 

 rocks lying upon green-slate. Lower down the rocks 

 take a basaltic aspect. Farther south the slates disap- 

 pear, being concealed under a trap deposite of varied 

 appearance, but assuming an amygdaloidal character, 

 and on the margin of the plam is seen a formation of 

 clinkstone or porphyry-slate. 



The travellers now entered the basin of the Llanos. Basin of the 

 The sun was almost in the zenith, the ground was at Llanos. 

 the temperature of 118° or 122°, and the suffocating 

 heat was augmented by the whirls of dust which inces- 

 santly arose from the surface of the steril soil. All 

 around, the plains seemed to ascend into the sky. The 

 horizon in some parts was clear and distinct, while in 

 others it seemed undulating or blended with the atmo- 

 sphere. The trunks of palm-trees, stripped of their 

 foliage, and seen from afar through the haze, resembled 

 the masts of ships discovered on the verge of the ocean. 



In order to give some mterest to the narrative of a American 

 journey across a tract of so monotonous an aspect, I'l'^s. 

 Humboldt presents a general view of the plains of 

 America, contrasted with the deserts of Africa and the 

 fertile steppes of Asia, of which, however, the most 

 striking points alone can be here taken. There is some- 

 thing awful and melancholy, he says, in the uniform 

 aspect of these savannahs, where every thing seems 

 motionless, and where the shadow of a cloud hardly 

 ever falls for months. He even doubts whether the 

 first sight of the Andes or of the Llanos excites most 

 .istonishment ; for, as mountainous countries have a 

 similarity of appearance, whatever may be the elevation 



