474 APPENDIX. 



student must never, in any thing, encumber his de- 

 scriptions with superfluous circumstances; while, if it 

 is the business of a discerning mind to select the use- 

 ful, even from what is unknown, this quality of philo- 

 sophical foresight cannot be communicated by any in- 

 structions. I must also call his attention to the con- 

 glomerates, hitherto so ill understood, to the connex- 

 ions of organic substances, especially of coal or lig- 

 nite, with them, to that frequently scoriform character 

 which proves their volcanic origin, above all to a careful 

 discrimination of the veins, lest he mistake them for 

 strata, and lastly, to those real strata which appear to 

 have been fused in situ. But the former history of these 

 substances will amply teach him what I need not fur- 

 ther enforce. Wherever, lastly, the country under 

 review combines existing, or admittedly antient vol- 

 canoes, with rocks of this class, unusual attention will 

 be required on a subject not yet sufficiently elucidated ; 

 while respecting volcanoes themselves, and their pro- 

 ducts, I can only suggest the necessity of scientific ex- 

 amination ; since, of the wonderful, we have already 

 more than enough. 



Respecting the stratified rocks, it must first be re- 

 membered that the order of succession is inconstant ; 

 so that they should be examined without any previous 

 hypothesis, and described as they exist. There is no- 

 thing in the whole circle of geology in which this rule 

 is more rigidly to be enforced ; since, in nothing, are 

 we now more deceived by fanciful and false statements. 

 And let every reader distrust or neglect him, who, in- 

 stead of duly searching, and simply and fully describ- 

 ing, adopts the system and phraseology in vogue. As 

 to the details, the first relate to the place and extent of 

 a given stratum, and to the inferences respecting its 

 probable continuity, when no longer to be fairly traced. 



