154 THE DESICCATION OF LATER GEOLOGICAL TIMES. 



desiccation in this portion of South America, and enters into a discussion as 

 to the causes of the phenomenon, to which we shall have occasion to revert 

 farther on. 



It seems unnecessary to multiply evidence of the kind given in the preced- 

 ing jiages. The fact cannot fail to have impressed the reader that, however 

 striking the phenomena of desiccation may have been shown to be in our 

 own western region, they are not less so in the Old World ; where we have 

 an additional interest imparted to the investigation, by the fact that we 

 have here to do with the historically important portion of the world, so that 

 the connection of the desiccation with the growth, migrations, and decay of 

 civilized nations makes it a matter of the utmost importance. In the course 

 of the next chapter additional information will be, of necessity, introduced, in 

 regard to the phenomena which have occupied us during the present one. 

 Having shown the fact of a desiccation going on at least during the later geo- 

 logical periods, and continuing up to the present day, certainly over a large 

 part of both hemispheres, in botli the Old and New Worlds, we are now pre- 

 pared to proceed with the discussion of the facts presented, and to endeavor 

 to ascertain what cause or causes have been influential in bringing about the 

 condition of things described. That the problem is a complicated and diffi- 

 cult one will not be denied ; but it is hoped that, in the following chapter, 

 some light will be thrown upon it, even if there are questions raised to 

 which it is not easy to give an entirely satisfactory answer. 



