636 



require to be made. No higher evidence can be conceived of the 

 vast knowledge and great sagacity of its author. 



Such modifications we must ever expect to have to make of afirst ap- 

 proximation ; and I should think it a misfortune to our researches if we 

 should attempt to elude this necessity by giving up the key of all 

 our geological knowledge of our country, — the doctrine that there is a 

 fixed order of strata, characterized mainly by their organic fossils. 

 If we have not advanced so far as to prove this, what have we proved ? 

 If our terms do not imply this, what is their meaning ? Is it not 

 true, in our science as in all others, that a technical phraseology is 

 real wealth, because it puts in our hands a vast treasure of foregone 

 generalizations ? And if we evade the difficulties which may occur in 

 the application of this phraseology to new cases, by declaring that our 

 terms are of little importance, is not this to deprive our language 

 of all meaning and all worth ? Do we not thus refuse to recognise 

 as valuable the tokens which we ourselves circulate, and plainly de- 

 clare ourselves bankrupts in knowledge ? When certain strata of 

 Devon have thus been identified with the coal measures of other re- 

 gions, can we still term them grauwacke ? Either this term implies 

 members having a definite place in our series of strata, or it does 

 not. If it do, it is certain that these strata have not that place. If 

 it do not, it conveys no geological knowledge at all. But if it be 

 used to imply a rejection of such series, it involves a denial of all 

 geological knowledge hitherto asserted concerning the older rocks of 

 this county. 



The transition downwards from the culmiferous beds of Devon to 

 the older strata on which they rest, is, according to almost all who have 

 studied the subject, wrapt in great obscurity. In this obscurity, if 

 it be true that the fossil plants of the culm measures are found also 

 in the subjacent rocks, there is nothing which need make us mistrust 

 the clear and positive part of our knowledge. And even if this be 

 so, it will not be the less necessary to separate the culmiferous from 

 the subjacent Silurian and Cambrian systems, by a different name 

 in our lists, and by a diiFerent colour in our geological maps, if they 

 are to represent the present state of our information. 



The interest of this question has induced me to dwell upon it 

 longer than I had intended, and I must on that account be very brief 

 in my notice of many other communications. I may observe that 



