E. E. Roicorth—A Great Post-Glacial Flood. 305 



wanderings and warfare of that people did very prevailingly take 

 place, and which from their original seat in Central Asia and their 

 imperial city of Khanbaligh spread to the west of Europe : if he 

 had, besides, taken the trouble to make himself acquainted with the 

 arguments of the existing theories respecting the mode of origin of 

 this soil before undertaking to put them aside ; and if he had for a 

 moment considered from a geological point of view a few of the 

 concomitant circumstances required by his own theory, he would 

 hardly have ventured to adopt views which could be pronounced at 

 an early and rather low stage of geological science, but are long since 

 abandoned, and he would never have added to them suppositions 

 which bear the character of the infancy of that science. If there 

 is any subject to which the theory of Mr. Howorth may be applieid, 

 it is, in a figurative way, the history of the Mongols. The crowds 

 in which they appear suddenly on the stage resembles the outpouring 

 of volcanic matter from a hidden source, and the flood of them 

 which soon inundated immense regions, " mixed with the ingredients 

 over which it poured," may indeed be compared to the action of a 

 sweeping wave. But the laws which govern the movements of 

 mankind have but a very distant relation to those which can be 

 discerned in the changes of the physical conditions of the surface of 

 the globe. F. Baron Eichthofen. 



Bonn, U'aij, 1882. 



IIL— Traces of a Great Post-Glacial Flood. 



3. The Evidence of the Valley Terraces. 



By H. H. Howorth, F.S.A. 



THE Terraces which are so conspicuous in many valleys of 

 Western Europe, and have been largely studied in France and 

 Britain, have given rise to a great deal of discussion. The polemics 

 which they have suggested have been not merely about details, 

 but about fundamental principles, and it is these fundamental 

 principles which are still unsettled and awaiting a solution. In 

 England at all events it may be said that every solution which is 

 current, and there are many, fails to meet the facts, and the majority 

 of them are singularly suggestive of the dangers of Deductive 

 methods of reasoning. So long as we start with a mere scholastic 

 premise that Uniformity of action is the only method pursued by 

 Nature, and having thus committed ourselves, try to bring the facts 

 within this rigid rule, so long are we necessarily inspiring our 

 witnesses with the answer we wish them to give us, and so long 

 shall we experience inevitable disappointment when some obstinate 

 fact refuses to submit to our self-imposed rule. We shall in the 

 following examination of the problem entirely discard this a priori 

 theological method of discussion, and lean to whatever conclusion 

 the facts themselves impose upon us. We must necessarily begin 

 with a somewhat elementary position. 



A river as a mechanical agent performs two entirely opposite 

 kinds of work upon its own channel. Where its fall is great and 



DECADE II. — VOL. IX. NO. VII. 20 



