106 Baron xilexander von Humboldt on (he Pliysiognomy 



and chalk were precipitated in a muddy condition, then the 

 outlines of these two formations indicate, for two epochs, the 

 boundary between the stilFstone-producing ocean and the solid 

 land which had previously been laid dry. The ingenious idea 

 has been suggested, of preparing maps of this physical portion 

 of ancient geography ; maps which, perhaps, are more trust- 

 worthy than those of the wanderings of lo or those of the 

 Homeric geography. The latter exhibit opinions and mytho- 

 logical representations ; the former present the earliest facts 

 of the positive doctrine of formations. 



The result of investigations regarding the superficial rela- 

 tions of dry land is, that in the earliest periods, viz. in the 

 Silurian and Devonian transition-epoch, as well as in the first 

 floetz period, including the trias, the uncovered surface which 

 was clothed by land plants, was limited to detached islands ; 

 that afterwards these islands were united with one another, 

 and included many lakes along the deeply penetrating bays 

 of the sea ; and, lastly, that when the mountain chains of tlie 

 Pyrenees, the Apennines, and the Carpathians Avere elevated, 

 therefore at the period of the deposition of the older tertiary 

 strata, vast continents, having nearly their present size, 

 made their appearance. In the Silurian world, as well as 

 during the period characterised by a profusion of Cycadeee 

 and by gigantic Saurians, the amount of dry land from pole 

 to pole was probably less than it is at present in the South 

 Sea and the Indian Sea. I shall afterwards explain how this 

 excessive prevalence of Avater, in combination Avith other 

 causes, contributed to the elevation of temperature, and to 

 the greater uniformity of climate. At present it is only 

 necessary to remai'k, in considering the gradual enlargement 

 (agglutination) of the elevated dry tracts of land, that shortly 

 before the revolutions AAdiich, after shorter or longer pauses, 

 produced, during the r/i/«ym/;;e;7W, the sudden destruction 

 of so many gigantic vertebrate animals, portions of the noAV 

 existing continental masses Avere then completely separated 

 from one another. Great similarity prevails in South Ame- 

 rica and Australia between the living and the extinct ani- 

 mals. In NcAV Holland, fossil remains of kangaroos have 

 been discovered ; and in NeAV Zealand, semifossil bones have 



