122 THE DESICCATION OF LATER GEOLOGICAL TIMES. 



square miles of territory,* of which a little over seventeen millions belong to 

 Asia projjer, this being considerably larger than the combined area of North 

 and South America. Here, too, we find the largest existing area of land 

 Avithout drainage to the sea, forming a series of closed basins, of which the 

 entire area is probably not less than three milhon square miles. This closed- 

 basin area is, in most respects, closely analogous to our own Great Basin, 

 but is on a much larger scale. Like that, it is intersected by numerous 

 more or less independent chains of mountains, which enclose valleys, some- 

 times narrow and limited in length, and in other cases of vast dimensions. 

 Often each one of these valleys forms an independent basin ; then again 

 several are connected together into one drainage system. An exactly simi- 

 lar condition prevails in our own Great Basin, in the driest portion of which 

 each separate valley is usually closed at both ends, as is the case with so 

 many of the depressions between the ranges in Southern Nevada, — while 

 in other cases an area of considerable magnitude may be drained towards a 

 central depression by means of one or more transverse breaks, crossing sev- 

 eral ranges, as is the case with tiie valley of the Humboldt River, and the 

 various side-valleys more or less perfectly connected with it. 



The Asiatic closed-basin region is centrally situated with respect to the 

 continental mass to wliich it belongs; while that of North America occupies 

 an area of an irregularly triangular shape, the southwestern corner of which 

 comes close to tlie Pacific, forming, in fact, a part of the Pacific slope, since 

 it is entirely surrounded by streams all of which empty into that ocean. — 

 for the branches of the Colorado and the Columbia head entirely to the east 

 of the Great Basin. In Asia, on the other hand, the drainage from the cen- 

 tral, elevated, and closed-basin region is radial, towards the Northern Oce.an, 

 the Indian Ocean, and the Pacific. And so vast is the continental mass that, 

 in spite of the immense size of the closed-basin area, the rivers descending 

 from its elevated borders, and flowing in each of the specified directions, are 

 of great size, so that a large number of them may be classed as rivers of the 



* The estimates of the areas of the various continental land masses, given in tlie text-liool;s of geography, dilTer 

 from each other in the most surprising manner ; tliat of Asia being especially uncertain, the figures in regard to 

 that country varying from fourteen to eigliteen njillion square miles. The latest and most trustworthy author- 

 ity (Behni und Wagner, in Erganzungsheft, No. 62, ISSO, to Petermann's Jlittheilungen) gives the area of Asia at 

 44,572,250 square kilometers, equal, in round numbers, to 17,200,000 English square miles. By the same au- 

 thority Europe is given at 9,710,340 square kilometers, equal, in round numbers, to 3,750,000 English square miles. 

 The combined area of Eurasia is, therefore, in round numbers, 20,950,000 square miles. The area of America 

 (North and South) is put down by Belun and Wagner at 38,389,210 square kilometers, or 6,183,040 square kilo- 

 rm;ters less than that of Asia (2,387,000 English square miles). 



