1832.] SAN SALVADOR. 25 



The elegance of the grasses, the novelty of the parasitical 

 plants, the beauty of the flowers, the glossy green of the 

 foliage, but above all the general luxuriance of the vegeta- 

 tion, filled me with admiration. A most paradoxical mixture 

 of sound and silence pervades the shady parts of the wood. 

 The noise from the insects is so loud, that it may be heard 

 even in a vessel anchored several hundred yards from the 

 shore ; yet within the recesses of the forest a universal 

 silence appears to reign. To a person fond of natural 

 history, such a day as this brings with it a deeper pleasure 

 than he can ever hope to experience again. After wander- 

 ing about for some hours, I returned to the landing-place ; 

 but, before reaching it, I was overtaken by a tropical storm. 

 I tried to find shelter under a tree, which was so thick that 

 it would never have been penetrated by common English 

 rain ; but here, in a couple of minutes, a little torrent flowed 

 down the trunk. It is to this violence of the rain that we 

 must attribute the verdure at the bottom of the thickest 

 woods : if the showers were like those of a colder clime, 

 the greater part would be absorbed or evaporated before 

 it reached the ground. I will not at present attempt to 

 describe the gaudy scenery of this noble bay, because, in 

 our homeward voyage, we called here a second time, and 

 I shall then have occasion to remark on it. 



Along the whole coast of Brazil, for a length of at least 

 two thousand miles, and certainly for a considerable space 

 inland, wherever solid rock occurs, it belongs to a granitic 

 formation. The circumstance of this enormous area being 

 constituted of materials which most geologists believe to 

 have been crystallised when heated under pressure, gives 

 rise to many curious reflections. Was this effect produced 

 beneath the depths of a profound ocean ? or did a covering 

 of strata formerly extend ovfer it, which has since been 

 removed? Can we believe that any power, acting for a 

 time short of infinity, could have denuded the granite over 

 so many thousand square leagues ? 



On a point not far from the city, where a rivulet entered 

 the sea, I observed a fact connected with a subject discussed 

 by Humboldt.* At the cataracts of the great rivers Orinoco, 

 Nile, and Congo, the syenitic rocks are coated by a black 

 substance, appearing as if they had been polished with 

 plumbago. The layer is of extreme thinness ; and on 

 analysis by Berzelius it was found to consist of the oxides 



* " Personal Narrative," voL v.i pt i,, p. i8. 



