68 THE POPULAR SCIENCE MONTHLY. 



section exposed, and in it the upper bowlder-clay, similar to that shown 

 in Fig. 2, at one end of the pit, gradually changes into a sandy loam 

 with stones and angular patches of sand, not to be distinguished from 

 the deposit named "trail" in Fig. 1. 



At Hoxne itself, on the east side of Gold Brook, there is a gravel- 

 pit showing seams of gravel and sand exactly similar to that at Syle- 

 ham, but surmounted by sandy " trail " instead of by bowlder-clay. The 

 gravel is not to be distinguished from the other, being composed like 

 it of subangular flint-pebbles with rounded ones of quartz and quart- 

 zite, and with many small pebbles of chalk in the lowest seams. Not- 

 withstanding this great similarity, Mr. Prestwich considers the beds 

 at Hoxne to have been formed by river-action in post-glacial times ; 

 while those at Syleham, being capped by bowlder-clay, he of necessity 

 classifies as middle glacial. Yet I could find no difference whatever 

 in their appearance or composition. In both the pebbles are mostly 

 small and subangular, with some rounded ones of quartz and quartzite. 

 Both contain many small pebbles of chalk in their lowest seams, and 

 both are false-bedded. That one is covered with bowlder-clay and the 

 other by sandy " trail " does not suffice to prove them of different age, 

 for at the Oakley gravel-pit we can trace the same gravels from one 

 end, where the bowlder-clay overlies them, to the other, where the 

 "trail" does so. The middle sands and gravels are generally sup- 

 posed by geologists to be marine, and it is incredible that deposits due 

 to such different agencies as that of the waves of the ocean beating on 

 a beach and that of a flooded river should be absolutely identical in 

 appearance and composition. But nowhere is either the ocean or any 

 river known to be forming deposits of subangular pebbles, excepting 

 where they are cutting into preexisting beds of the middle glacial series. 

 Both in sea and in river beaches the pebbles are smoothly rounded, and 

 not, as in the gravels under consideration, broken and subangular. 

 Even when we find in the latter rounded pebbles of tertiary age there is 

 often a piece chipped out of them as if they had been dashed violent- 

 ly together. I have had a large number of the pebbles from the gravel 

 at Ealing counted, and find that over eighty per cent, are broken or 

 subangular. I ask where, in the whole world, is such a deposit being 

 formed by existing agencies ? Surely, if ordinary floods would pro- 

 duce them, they have had plenty of opportunities of doing so during 

 the past pluvial year ; yet where, on the banks of any of our rivers, 

 have the great floods left deposits even approaching in character to 

 those that geologists confidently ascribe to river-action ? That they 

 w r ere caused by a great flood I fully believe, though not by that of any 

 river, but by one that swept over the whole country, driving a huge 

 mass of gravel and sand, and leaving them mantling both hills and 

 valleys, holding or covering up the remains of palaeolithic man and the 

 great mammals that had lived before the waters w r ere pent up by the 

 Atlantic glacier. 



