S. E. Hoicorth— Traces of a Great Post-GIacial Flood. 513 



seaboard to the height of 222 feet inland, are good evidences that 

 these creatures were destroyed by violent oscillations of the land, 

 and were swept by currents of water from their feeding grounds into 

 the hollows in which we now find them, and where the argillaceous 

 materials which covered them have favoured their conservation. 

 Nothing can more strongly favour this view than the manner in 

 which fragments of chalk-flints, often angular, are wedged together 

 in tlie matrix of loam, and enter into the cavities of some of the 

 vertebree and broken bones of the lai'ge quadrupeds" (Journ, Geol. 

 Soc. vol. vii. p. 386). 



Lastly, after contrasting the angular flints we are discussing with 

 the rouuded flints of the Thames Valley, and urging that the roiind- 

 ing of the latter was an operation of the early Tertiary period, 

 Murchison goes on to say that " from the slopes of the South Downs 

 to the sea, where very few rounded Tertiary pebbles have ever 

 existed in situ, we clearly see that after the first rush of waters, 

 whether down the talus of the chalk or through lateral openings, 

 the fractured flints must have been left as originally piled up, and, 

 being desiccated, have never more been subjected to the action of 

 water and have remained in their angular state" {id. p. 389). These 

 extracts from Murchison might be greatly extended ; for the very 

 long and remarkable paper which is here quoted, and which to my 

 mind is one of the most acute and profound ever written by the 

 famous author of the Silurian System, is devoted to urging that the 

 distribution of the surface deposits of South Britain requires for its 

 explanation such a cause as we are arguing for. Fi'om the weighty 

 opinion of Murchison we may turn to the equally weighty opinion 

 of Mr. Prestwich. 



Mr. Prestwich read a paper before the Geological Society on the 

 25th of June, 1851, in which the following remarkable passage 

 occurs : " In a paper on the Brighton Drift (i.e. the paper just 

 cited), Sir Eoderick Murchison expressed an opinion that the accu- 

 mulation of the Mammalian chalk and flint rubble was sudden and 

 tumultuous. In this view I quite agree, and also conclude that the 

 same rapid mode of accumulation is to be attributed to the Sangatte 

 Drift. For if the action had been slow and gradual, the rolling to 

 which the broken flints would have been subjected must inevitably 

 have more or less blunted their edges ; and further, any rounded 

 flint pebbles from the Tertiary strata would only have heen more 

 rolled and rounded. But, on the contrary, we find in this chalk- 

 rubble broken angular flints with edges as sharp as a knife, and 

 with fractures as clean as though they were just broken with a 

 hammer, while the small, hard, round flint pebbles from the Tertiary 

 strata are often broken in two or more pieces, and these pieces 

 neither rolled nor worn. Some which are entire, and likewise many 

 of the flat broken lumps of iron-sandstone, are also found, as it were, 

 standing on end, their longer axes perpendicular to the lower 

 surface of the deposit. Again, with regard to the finer sediment, if 

 the accumulation had been tranquil, this would have tended to have 

 formed separate and distinct layers ; whereas we find an almost 



DECADE II. — TOL. IX. — NO. XI. 33 



