64 THE POPULAR SCIENCE MONTHLY. 



valley-gravels. They are found mixed through them, or more com- 

 monly at their base. Palaeolithic implements are found in the same 

 position, though usually in gravel higher up on the slopes of the val- 

 leys. When found in the gravel, the bones are broken and worn, and 

 the flint implements have their angles rounded more or less as if by 

 rolling. When, as has happened in a few cases, the bones and imple- 

 ments have been found below the gravels, they have betn uninjured 

 and unworn. Mr. Godwin Austen noticed the occurrence of bones of 

 the mammoth in an old forest-bed beneath the valley-gravels, at 

 Peasemarsh, in Surrey, uninjured and lying together, while in the 

 overlying gravel the teeth of the mammoth were found singly and 

 rolled. 1 And Colonel Lane Fox has recorded the discovery of flint 

 implements at Acton in seams of white sand, nine feet from the sur- 

 face, beneath deposits of giavel and brick-earth. 2 Their edges were 

 as sharp as if just flaked off a core of flint ; while those found in the 

 gravel, on the contrary, have their edges worn and rounded just like 

 those of the subangular pebbles of which the gravel is principally 

 composed. 



The position and the state of preservation of the bones and imple- 

 ments are such as might be expected if they had been deposited on 

 an old land-surface before the outspread of the gravels, when the con- 

 figuration of the country was much the same as now ; and I have sug- 

 gested that the occurrence of the implements, generally higher up the 

 slopes of the valleys than the mammalian remains, is due to palaeo- 

 lithic man having frequented more elevated and drier localities than 

 the great mammals. I have urged that the outspread of the gravels 

 was due, as formerly supposed by Sedgewick, De la Beche, and Mur- 

 chison, to the action of a great flood or debacle. I have advanced the 

 theory that that debacle was caused by the breaking away of a bar- 

 rier of ice that blocked up the English Channel, and with it nil the 

 drainage of Northern Europe, causing .an immense lake of fresh or 

 brackish water that was thus suddenly and tumultuously discharged. 3 



This great flood occurred, according to my theory, before the cul- 

 mination of the Glacial period, and was primarily due to ice filling the 

 bed of the North Atlantic as far south on the European side as lati- 

 tude 49. If the gravels in and below which the rude flint imple- 

 ments and the remains of the extinct mammals are found, were thus 

 spread out, it follows that they were preglacial in the sense that they 

 lived before the principal glaciation of the country. 



We have seen that, in the north, such an excellent geologist as 

 the late Prof. Phillips had arrived at this conclusion with regard to 

 the age of the mammoth, the woolly rhinoceros, and the hippopota- 



1 Quarterly Journal of the Geologiccd Society, vol. vii., p. 2S8. 



2 Ibid., vol. xxviii., p. 456. 



3 Quarterly Journal of Science, April, 1875. Quarterly Journal of the Geological 

 Society, vol. xxxii., p. 84. 



