FUTURE POSITIONS OP 



World the Mississippi, Orinocco, Amazon, and 

 are all projecting their vast deltas within these warmer 

 zones ; so also are the larger rivers of Europe and Africa, 

 for though the Nile has a northerly trend, its delta is still 

 within these warmer limits ; and so also are the more im- 

 portant delta-formers of Asia the Tigris and Euphrates, the 

 Indus, Ganges, Irawaddy, Menam, Kong, Yang-tse-Kiang, 

 and Hoang-ho. One has only to cast his eye over a map 

 of the " river-systems," to perceive the truth of this asser- 

 tion; for though Siberia and Arctic America are also pos- 

 sessed of large rivers, their ice-bound character and other 

 conditions render their laniforming powers comparatively 

 unimportant. To this southerly projection of the great 

 rivers must also be added the fact, that vulcanic agency 

 is much more active in its accumulations within tropical 

 and sub -tropical than within arctic or antarctic zones. 

 Appeal to any volcanic map of the world, and see how 

 blank and quiescent are the great tracts of North America, 

 Northern Europe, and Northern Asia, as compared with 

 the warmer and more southerly zones, and then judge how 

 much this may have to do with the formation and disposi- 

 tion of the future continents. In all the formations of 

 newer lands vulcanicity has played an essential part ; can 

 we fail to infer that the vast cincture of volcanic action 

 that surrounds the Pacific, as well as the numerous centres 

 that stud its basin, are intimately connected with the ela- 

 boration of future land-masses within its area ? It is true 

 that the gradual elevation noted by voyagers among the 

 Arctic Islands, Northern Greenland, Spitzbergen, Scan- 

 dinavia, and Siberia, would seem to point to a more con- 

 tinuous massing of the land in that direction ; but though 

 this were to be the case, it would not interfere with the 

 likelihood of our previous surmise, that the dry lands more 

 immediately succeeding the existing will lie within more 



