36 Remarks on the Geological Principles 



ling my voyage, and during my stay at the Cape, and the Isle 

 of France, and my residence at this place. 



I remain, &;c. 

 Colombo, Nov. 3, 1S16. JoHN DaVY. 



VII. Remarks oH the Geological Principles of' Werner, and 

 those of Mr. Smith. By Thomas Tredgold, Esq. 



To Mr. Tilloch. 



Sir, — AN the last number of the Edinburgh Review it is stated, 

 that " it has been proved (and Werner was the hrst to make 

 the observation) that the masses or strata that constitute the 

 surface of the globe, present themselves in groups or assem- 

 blages, the members of which are generally associated, whenever 

 they occur, and are so connected as to exhibit a certain unity of 

 character. 



" To such assemblages Werner gave the name oi' J arm a/, iojis ; 

 and his doctrine (or hypothesis, if this latter term be preferred) 

 is, that the exterior oj' the earth co?isists of' a series of these for- 

 mat ions, laid over each other, in a certain determinate order. 

 Not that the whole series is anywhere complete ; but that the 

 relative place of its several members is never departed from. 

 Thus, in a series A, B, C, D, it may happen that B or C, or both, 

 may be occasionally wanting, and consequently D be found im- 

 mediately above A ; but the succession is never violated, nor the 

 order inverted, by the discovery of A above the formations B or 

 G, or D, nor of B above those that follow it, &:c." 



" The only rival claimant to this doctrine, that we know of, 

 is Mr. William Smith, the publisher of the Geological Map of 

 England that has recently made its appearance — a work which 

 it would be unjust to mention without adding, that it is of great 

 and original value,; indeed, regarding it as the production of an 

 unassisted individual, of most extraordinary merit. For although 

 the publication of this map was delayed till the year 1815, we 

 liave no doubt that Mr. Smith's acute and laborious researches 

 originated entirely from the facts which came before him in ex- 

 amining the stratification of England many years ago; and that 

 he was then, and long afterwards, wholly unacquainted with what 

 had previously been done by Werner. The opinions of Mr. 

 Smith, however, so nearly coincide with the doctrine oi forma- 

 tions which we have just stated, that it would be difficult to ex- 

 press them in any other terms *." 



From this quotation it appears, that this eloquent writer is 

 * Edinburgh Review, No. Ivii. p. 71- 



better 



