756 DYNAMICAL GEOLOGY. 



current. Sinking the land about Behring Straits, so as to let the 

 Japan current flow freely into, and distribute itself along with the 

 Gulf Stream through the Arctic, would, as F. H. Bradley has sug- 

 gested, especially if the Arctic lands were low, make all the warm 

 temperature there that the forest vegetation of the Miocene might 

 have demanded. And it is probable that the closing of the same polar 

 region to both of these tropical flows would aid much toward produ- 

 cing, as stated on page 541, the Arctic climate of the Glacial period. 



Again, if ever the region of the Red Sea and Mediterranean gave 

 free passage to the current of the Indian Ocean, this would have had a 

 warming effect over all Europe, and even in the Arctic regions. On 

 the contrary, if southern South America, up to latitude 30°, were 

 deeply submerged, it would give passage into the Atlantic of the great 

 frigid current that now carries cold along the west coast of South 

 America to the Galapagos, under the equator, and the whole Atlantic, 

 north and south, and the neighboring continents, would feel its chilling 

 influence. As to the sinking of the Isthmus of Darien, it is not 

 probable that it has been deeply enough submerged, at any time since 

 the Paleozoic, to affect appreciably the flow of the Gulf Stream in 

 the Atlantic, or of the Antarctic current of the Pacific. 



VII. PROGRESS IN ACCORDANCE WITH THE UNI- 

 VERSAL LAW OF DEVELOPMENT. 



The general law at the basis of all development is strikingly ex- 

 hibited in the earth's physical progress, as has been well shown by 

 Guyot. The law is simply this : Unity evolving multiplicity of parts, 

 through successive individualizations, proceeding from the more funda- 

 mental onward. 



The earth in igneous fusion had no more distinction of parts than a 

 germ. Afterward, the continents, while still beneath the waters, began 

 to take shape. Then, as the seas deepened, the first dry land ap- 

 peared, low, barren, and lifeless. Under slow intestine movements, 

 and the concurrent action of the enveloping waters, the dry land ex- 

 panded, strata formed ; and, as these processes went on, mountains by 

 degrees rose, each in its appointed place. Finally, in the last stage 

 of the development, the Alps, Pyrenees, and other heights received 

 their majestic dimensions ; and the continents were finished to their 

 very borders. 



Again, as to the history of fresh waters. The first waters were all 

 salt, and the oceans one, the waters sweeping around the sphere in an 

 almost unbroken tide. Fresh waters left their mark only in a rain- 

 drop impression. Then the rising lands commenced to mark out the 



