216 VIEWS OF NATURE. 



our civilization. The great catastrophe by which the Medi- 

 terranean was formed, when the swollen waters of an inland 

 sea burst their way through the Dardanelles and the Pillars of 

 Hercules, appears to have stripped the contiguous lands of 

 a large portion of their alluvial soil. The records of the 

 Samothracian traditions (8) preserved by Greek writers seem 

 to indicate the recent date of this great convulsion of nature. 

 Moreover, in all the lands bathed by the Mediterranean, and 

 which are characterised by the tertiary and cretaceous forma- 

 tions (Nummulites and Neocomian rocks), a great portion, of 

 the earth's surface is naked rock. The picturesque beauty of 

 Italian scenery depends mainly on the pleasing contrast 

 between the bare and desolate rock and the luxuriant vegeta- 

 tion which, island-like, is scattered over its surface. Where 

 the rock is less intersected by fissures, so that the water 

 rests longer on its surface, and where it is covered with earth 

 (as on the enchanting banks of Lake Albano), there even 

 Italy has her oak -forests, as shady and verdant as could be 

 desired by an inhabitant of the North. 



The boundless plains or steppes of South America, and the 

 deserts beyond the Atlas range of mountains, can only be 

 regarded as mere local phenomena. The former are found to 

 be covered, at least in the rainy season, with grasses and low 

 almost herbaceous Mimosa? ; while the latter are seas of sand 

 in the interior of the Old Continent, — vast arid tracts sur- 

 rounded by borders of evergreen forests. Here and there only 

 a few isolated fan-palms remind the wanderer that these 

 dreary solitudes are a portion of animated nature. Amid the 

 optical delusions occasioned by the radiation of heat, we see the 

 bases of these trees at one moment hovering in the air, at the 

 next their inverted image reflected in the undulating strata 

 of the atmosphere. To the west of the Peruvian Andes, 

 on the shores of the Pacific, I have passed weeks in tra- 

 versing these waterless deserts. 



The origin of this absence of plants over large tracts of 



