E. E. Hoicorth — A Great Fod- Glacial Flood. 417 



wliicli in fact represent tlieir old banks when so flooded. Two 

 causes for such abnormal floods have been assigned. Mr. Tylor 

 postulates a Pluvial period, characterized by most exceptional rainfall; 

 while Mr. Belt urges that these floods were caused by the pounding 

 back of the European rivers, and the consequent formation of a 

 European lake by a great Atlantic glacier. 



Both these theories, like those which have been already examined, 

 in claiming the rivers or a lake, either in their normal or abnormal 

 conditions, as the depositors of the terraces, fail to meet the 

 supreme difficulty we have pointed out before, that the deposits 

 are not fluviatile or lacustrine at all. Their contents prove them 

 to be other than river or lake deposits, either of normal rivers or 

 lakes, or rivers or lakes expanded by abnormal floods. Thei-e is 

 another reason equally potent. If these deposits were the result of 

 successive river floods, or of river floods distributed over a long 

 period, we should assuredly have the deposits arranged in layers, 

 marking the secular variations of the watei', such as we find in all 

 river-warp and similar deposits. Here, however, we have no such 

 facts, but the gravels, sands, and loam are deposited according to the 

 laws of gravity, as they would be deposited by one supreme effort. 



That the gravels were deposited where they are now found by 

 water, and water in rapid motion, is inevitable ; that this water must 

 have filled up the vallej^s at least to the height of the upper layer of 

 gravel is equally inevitable ; but that this water should have been 

 merely the present rivers, swollen by abnormal rainfall, seems 

 assuredly incredible. With the present water-shed and drainage we 

 cannot conceive such floods, caused merely by rains, without postu- 

 lating a quite transcendental meteorology. 



Mr. Tylor does not in fact argue that such a rainfall as he requires 

 is possible with the climatic conditions now in vogue, but he boldly 

 accepts the position that climatic conditions were at that time entirely 

 different. He attributes the enormous rainfall of his Pluvial period 

 to " the sun's influence, which induced a much greater amount of 

 simshine in summer and a corresponding diminution in winter;" but 

 where have we any warrant for such an hypothesis ? In regard to 

 the meteoi'ological conditions of the climate when the gravels and 

 river terraces were laid down, we have the best of all barometers 

 ready to our hands in the abundant remains of plants and animals, 

 which not only mark the mean temperature, but limit also the 

 extremes ; and this barometer, with manifold readings all concurring 

 in one conclusion, is surely conclusive that the climatic conditions of 

 this period were such as prevail now in our temperate latitudes, and 

 quite inconsistent with those required by the hypothesis of Mr. 

 Tylor, and which are necessary if we are to secure such an abnormal 

 rainfall as 300 inches annually in England. 



A fall of rain in temperate latitudes on this gigantic scale is 

 assuredly a contingency verging on the impossible, and especially 

 when we are told that such a rainfall was not a mere exceptional 

 feature, but characterized a whole geological period, to which Mr. 

 Tylor has given the name of the Pluvial period. 



DECADE II. — VOL. IX. — NO. IX. 27 



