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SCIENCE-GOSSIP. 



PLEISTOCENE DRIFT OF THAMES VALLEY 

 By J. P. Johnson. 



HpHE series of old fluviatile deposits which 

 border the Thames and its tributaries, 

 known collectively as the river drift, consist 

 chiefly of gravel, often mixed with interbedded 

 lenticular patches of sand, and occasionally 

 almost entirely replaced by sand. In some places 

 there is a capping of loam, and below London 

 thicker masses of a similar character occur, 

 alternating with gravel and sand. The great bulk 

 of the gravel is composed of subangular flints 

 derived from the adjacent chalk. Mixed with 

 these are rounded flint pebbles washed from the 

 Eocene strata of the neighbourhood, together with 

 occasional pebbles of quartz, slate and other rocks. 

 When the gravel rests directly on the chalk it is 

 generally mixed at the bottom with a large 

 proportion of chalk rubble, which is sometimes 

 consolidated and forms a thin solid base to the 

 drift. The gravel is rarely more than six metres 

 in thickness; the loam is usually much less, but is 

 occasionally more. In the neighbourhood of 

 Hornchurch, in Essex, these deposits rest upon the 

 moraine material of ancient glaciers, and are hence 

 locally post-glacial. 



These accumulations of river drift mount up the 

 sides of the valley by a succession of broad terraces, 

 but sometimes they lie evenly on gentle slopes. Each 

 terrace forms a more or less flat tract, often cut 

 through by the main valley, or by side valleys, 

 sufficiently deep to lay bare the strata below the 

 gravel. The drift of the Thames Valley is evidently 

 the deposit of a river which was considerably 

 larger than its modern representative. This is 

 shown by the far wider tract within which it 

 flowed, whilst the comparative coarseness of its 

 deposit would indicate that it must have been of 

 a more torrential character. That condition of 

 size and power would be due for the most part 

 to greater height of the land, causing more 

 abundant condensation of atmospheric moisture 

 and heavier fall of rain or snow, There may, too, 

 have been a steeper slope of the river-bed, which 

 would give more power of transport. Such a 

 raising of the land would make our island part of 

 the main continent of Europe, as it undoubtedly 

 was at that period. 



The river drift of this region is very foesiliferous 

 in places. All the Mollusca represented, with the 

 exception of three, Unio littoralis, Corbiculaflaminalis, 

 and Paludestrina marginata, exist at the present day 

 in this island, whilst those three are now found 

 elsewhere. The remains of the Vertebrata, how- 

 ever, are the most interesting. Some, which are 



represented, still inhabit this country, such are the 

 fox (Canis vulpes), the otter (Lutra vulgaris), the stag 

 (Cervus elaphus), and the horse {Equus caballus). This 

 last was not then the fine large beast which the care 

 and training of man has produced — indeed it was 

 scarcely larger than a donkey. The wild cattle of 

 Chillingham Park may perhaps be the last surviving 

 descendants of Bos primigenius ; but if so, they are 

 considerably reduced in size. The majority, 

 however, of the animals which were contem- 

 poraneous with the primitive men who then 

 roamed by what is now the Thames Valley, are 

 no longer inhabitants of this country. Some 

 are extinct, though others survive elsewhere. 

 Amongst those species included in the former 

 category may be mentioned three rhinoceroses, 

 Rhinoceros antiquitatis, R. Icptorhinus, R. megarhinus, 

 and two elephants, Elephas antiquus, and E, 

 primigenius. The last-named was present through- 

 out the Glacial epoch, being well protected from 

 the severe climate by its woolly coat. The present 

 distribution of the survivors is of great interest. 

 The hippopotamus (Hippopotamus amphibius), the 

 hyaena (Hyaena crocuta) and the lion (Felts ho) are 

 now practically confined to the African continent, 

 but in Pleistocene times these three roamed over 

 Europe, and left their bones in the silt of the 

 ancient Thames. The occurrence of Ovibos moschatus 

 in these deposits is especially noteworthy, this 

 animal being now confined to the arctic regions of 

 North America. The grizzly bear (Ursus horribilis) 

 of the Rocky Mountains was here, and doubtless 

 often struck terror into the breasts of the savage 

 men. Vast herds of reindeer (Rangifer tarandus) 

 browsed on the banks of the Thames in company 

 with the gigantic extinct deer (Cervus giganteus). 

 Some of the smaller mammals, such as the beaver 

 (Castor fiber), have disappeared from these isles 

 within historic times, and several linger on in parts 

 of Europe : for instance, the wild-boar (Sus scrofa), 

 a variety of the European bison (Bison bonasus), the 

 wild-cat (Felis catus), the wolf (Canis lupus) and the 

 brown bear (Ursus arctos). Such was the remark- 

 able assemblage of animals which confronted 

 primitive man in the Thames Valley. Many 

 other fierce carnivora were associated with him 

 in Britain at this time, but I have only mentioned 

 the more important of those animals whose 

 remains have actually been found within this 

 restricted area. 



Man's presence is fully indicated by the abun- 

 dance of his rudely-made flint implements, though 

 his bones are extremely rare. The implements 



