On the Stratification of England, die 45 



Mr. Smith may be well entitled to denominate the London 

 clay, from the circumstance of the metropolis and its en- 

 virons (where alluvial gravel, sand, &c. or peat do not in- 

 tervene) standing immediately upon a very considerable and 

 remarkable red clay layer or stratum, forming part of this 

 uppermost assemblage of the British strata. It id not my 

 present intention, nor would it be proper towards my friend 

 Mr. Smith, to attempt, were I able, completely to develop 

 the theory which the immense body of facts in his posses- 

 sion (and numerous others in my own, collected before and 

 since 1801, when I first became acquainted with Mr. Smith) 

 go to establish: suffice it to say, that the most complete and 

 certain rules have been, or may in every instance be^ de- 

 duced for ascertaining the relative position (which pro- 

 bably never varies) of each distinct stratum, however thin, 

 with regard to those above and below it in the series (or 

 natural order of the strata, as Mr. Smith called it in his 

 first printed prospectus) ; rules equally general have, or will 

 on sufficient inquiry, be found, for identifying each parti- 

 cular stratum, either by the knowledge of its relative po- 

 sition with other known strata in its vicinity, by the pe- 

 culiar organized remains imbedded in it, and not to be 

 found in the adjoining strata, or by the peculiar nature and 

 properties of the matter composing the stratum itself. By a 

 reference to the rules above alluded to, and the considera- 

 tion of other well-established and unvarying particulars, the 

 alluvial matters can be certainly distinguished ; by which 

 term are here meant, the fragments of the regular strata, 

 more or less mixed with each other, or with extraneous 

 matters, and rounded or worn, lying upon the regular strata 

 (for such are rarely or probably never seen in or under the 

 sft-ata) and are there found deposited, apparently by the action 

 of violent currents of water (assisted perhaps by the general 

 principle of gravity, in circumstances which have never yet 

 been contemplated among the physical inquiries of mathe- 

 maticians), the manner of these alluvial deposits being per- 

 fectly different from, and apparently regulated by laws 

 quite dissimilar from those which obtained when the de- 

 position of the strata took place. A further remark it is 



essential 



