418 E. E. Eoivorth — A Great Post-Ohcial Flood. 



Mr. Tylor points to the tremendous rainfall that occasionally 

 occurs in the plains of Scinde, to which might be added Brazil, 

 Central America, etc., etc. All this is perfectly true, but in all 

 these cases the meteorological conditions are entirely different. To 

 import " the Eainy Season " or the torrential rains of the Tropics 

 into our temperate climate, and into our part of the earth's surface, 

 is a postulate which demands certainly very rigid proof. That 

 the warm winds heavily charged with moisture moving westward 

 from the Mid- Atlantic should be stopped by the high barriers of 

 the Andes, and the similar warm winds from the Indian Ocean 

 should be similarly stopped by the Himalayas, and in either case 

 should be forced to discharge their contents in vast sheets of rain 

 upon the intervening plains, is not only natural but is a necessary 

 conclusion. There are no such conditions available here. We 

 cannot suppose that the North Atlantic was ever the nursery 

 of such heavily charged warm winds as the Mid-Atlantic, nor 

 have we impassable mountain barriers in Europe to force these 

 winds to discharge their contents in any way comparable to the 

 rains of the Tropics. But even if we granted the conditions of the 

 tropics as possible, we are still very far from having secured a 

 sufficient amount of water to fill up the river valleys of Western 

 Europe, in some cases to the brim, and in most to a height of 

 several hundred feet. Mr. Prestwich states the conditions with 

 his usual force. '^ The greatest flood of the Seine on record," he 

 says, "is that of the year 1658, when it rose to a height of 29 feet. 

 Even in this case a flood of nearly sixty times that magnitude 

 would be required merely to fill the valley to the level of the 

 high-level gravels, without taking into consideration the more rapid 

 discharge ; but neither in this nor in the other cases of modern times 

 are we aware of an increase in the volume of water during floods 

 in these regions to many times the ordinary mean average, whereas 

 we see that in a case such as is presented at Amiens a flood 

 having a volume five hundred times that mean would be required 

 to reach the beds of St. Acheul " (Philosophical Transactions, 1864, 

 p. 266). But, granting that the meteorological conditions are 

 admissible, which we altogether question, we have still greater 

 difficulties behind. Mr. Tylor urges repeatedly, and it is in fact 

 the burden of his argument, that the enormous rainfall he postulates 

 (many times greater than that prevailing now) would greatly 

 increase the velocity of the streams and rivers, and thus explain 

 the great erosions which, he contends, are witnessed by the deposits 

 in dispute. " Ancient rivers," he says, "may have had many hundred 

 times as much destructive effect on the surface of the eaith, for 

 erosive force increases in the fourth power of the velocity, and may 

 have eroded the surface of the earth as much in former times in 

 one year as they now do in 1000, in cases where rocks were 

 made to slide on clay by excessive supply of percolated water " 

 (Geol. Mag. 1875, Decade II. Yol. II. p. 459). In all this we 

 seem to be on the track of most misleading analogies, and to be 

 led away by a postulate which Mr. Tylor quotes more than once, 



