464 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 19, 



Near the mouth of the Brent, at Kew, piles may he seen heneath 

 the Avater, marking, no douht, the site of a river habitation, similar 

 to those of the Swiss lakes ; and at Barnes, in the opposite bend of 

 the river, similar piles have been found, associated with a number of 

 flint celts and dolichocephalic skulls of the form believed to have 

 belonged to the earliest inhabitants of these islands. As these relics, 

 to the best of my belief, are not found in the Thames valley elsew^here 

 than in the existing bed of the Thames, it follows that the river must 

 have flowed in the same meandering course for two thousand years, 

 and in all probabilitj^ for a much longer period, the bed of the river 

 having actually risen during this period, as appears by the depth at 

 which these ancient relics are found beneath the sedimentary de- 

 posits*. We are thus led to form an idea of the enormous time that 

 would have been required to erode the whole valley by means of a 

 river flowing under the same conditions as the present one, to effect 

 which it would have been necessary for the river not only to have 

 shifted its bed over every portion of the present surface of the valley, 

 but to have done the same thing repeatedly at diff'erent levels, over 

 an extent of country which, as shown by the section, must, on the 

 100-feet line, have exceeded four miles and a half. This theory of 

 the gradual erosion of the valley by means of a river of the same size 

 as the present one, however, appears to have been abandoned by some 

 of the best authorities. 



The presence of lai'ge tracts of brick- earth overlying the gravel, 

 argues, as I venture to think, the existence of large volumes of 

 water at the time they were deposited. Then to Avhat cause are we 

 to attribute the strips of the London Claj^ laid bare on the sides of 

 the valley, and of the tributary streams, at the average level of 50 

 feet? Obviously to denudation of some kind. Why, then, is this 

 denudation not continued along the sides of the same streams into 

 the mid terrace and down to the present river ? The mid terrace, 

 instead of being broken into patches by denudation, like the high 

 terrace, is continuous, following the sinuosities of the valley up to 

 the limit of the 50 -feet line, or thereabouts. I venture to suggest, 

 though not without diffidence, that a body of water, occupying the 

 whole valley up to the 50 -feet line, would account for the pheno- 

 mena presented. The denudation of the patches of the high terrace 

 would be caused hj the drainage into this body of water. The mid- 

 terrace gravel would be the result, in a great measure, of accumula- 

 tions betieath the surface of the water. If this hypothesis were 

 admitted, the implements of the high terrace must belong to a 

 period anterior to that at which the river or lake stood at this 

 level ; and there is no reason, therefore, why they should not be 

 found in the gravels still higher above the riverf. 



The presence of these implements in the high terrace, their absence, 

 so far as our researches go, in the mid terrace, and their reappear- 



* The stone implements, I uBderstand from Mr. Layton, are found lower than 

 the bronze. 



t I may here notice that no shells of any kind were found in the sands, although 

 they were carefully looked for 



