6 CHANGES OF LETEL. 



soil between Valencia and G-uigue, the little hills rising 

 abruptly in the plain east of the Cano de Cambury, some of 

 which (el Islote and la Isla de la Negra or Caratapona) 

 have even preserved the name of islands, sufficiently prove 

 that the waters have retired considerably since the time of 

 Oviedo. "With respect to the change in the general form 

 of the lake, it appears to me improbable that in the seven- 

 teenth century its breadth was nearly the half of its length. 

 The situation of the granite mountains of Mariara and of 

 Guigue, the slope of the ground which rises more rapidly 

 towards the north and south than towards the east and 

 west, are alike repugnant to this supposition. 



In treating the long-discussed question of the diminution 

 of the waters, I conceive we must distinguish between the 

 different periods at which the sinking of their level has 

 taken place. Wherever we examine the valleys of rivers, or 

 the basins of lakes, we see the ancient shore at great dis- 

 tances. No doubt seems now to be entertained, that our 

 rivers and lakes have undergone immense diminutions ; but 

 many geological facts remind us also, that these great 

 changes in the distribution of the waters have preceded all 

 historical times; and that for many thousand years most 

 lakes have attained a permanent equilibrium between the 

 produce of the water flowing in, and that of evaporation and 

 nitration. "Whenever we find this equilibrium broken, it 

 will be well rather to examine whether the rupture be 

 not owing to causes merely local, and of very recent date, 

 than to admit an uninterrupted diminution of the water. 

 This reasoning is conformable to the more circumspect 

 method of modern science. At a time when the physical 

 history of the world, traced by the genius of some eloquent 

 writers, borrowed all its charms from the fictions of imagi- 

 nation, the phenomenon of which we are treating would 

 have been adduced as a new proof of the contrast these 

 writers sought to establish between the two continents. 

 To demonstrate that America rose later than Asia and 

 Europe from the bosom of the waters, the lake of Tacarigua 

 would have been described as one of those interior basins 

 which have not yet become dry by the effects of slow and 

 gradual evaporation. I have no doubt that, in very remote 

 times, the whole valley, from the foot of the mountains of 



