Correspondence^ Mr, S. V. Wood, 



the brickfield at Crayford forms 

 a higher terrace, as shown in 

 my section at page 409 of the 

 twenty-third volume of the Quar- 

 terly Journal Gcol. Soc. 



While Mr. Dawkins reserves 

 a doubt whether the brick-earth 

 of Dartford Heath and Hill- 

 house be identical with that of 

 Crayford, it is not worth while 

 attempting to show that it is 

 inferior to the Thames gravel ; 

 otherwise, I think means could 

 be found to satisfy even himself 

 of that fact. 



Mr. Dawkins' position gene- 

 rally is — first, That the chief 

 part of the deposits of the 

 Thames valley are older than 

 the Glacial clay of the northern 

 heights ; and the rest, viz., 

 what he and Mr. Fisher term 

 " Trail " (but whose existence 

 as a formation I do not admit), 

 is S3''nchronous with that clay ; 

 and — secondly. That the main 

 features of the country around 

 the Thames area were sketched 

 out before the Glacial clay pe- 

 riod. With respect to the first 

 of these propositions, I ask Mr. 

 Dawkins either to show that 

 section four at page 398,^ and 

 section thirteen at page 409, of 

 the twenty-third volume of the 

 Quarterly Journal, and the sec- 

 tion I now give are incorrect ; 

 or else to explain by what con- 

 dition of things such a structure 

 as they display could on his hy- 

 pothesis come to pass. Those 

 who know the Thames valley 

 are aware that a large arm of the 

 chief deposit in it, the gravel, 

 runs up the vallej^ of the Lea. 

 Now the accompanying section 

 shows the relation borne by 

 this gravel to the Glacial clay, 

 both in the Thames and Lea 

 valleys; as well as the struc- 



1 By oversight the elevation of Upmin- 

 ster Hall and Cranham Church is made too 

 great in this section, but this has no bear- 

 ing upon the structure displayed by it. 



Thames River at 

 Crossness Well 

 boring 



