LETTER XX. 



EXAMINATION OF OPINIONS, RESPECTING THE ORIGIN OF PEAT 

 ....ABORIGINAL FORM AT1ON.... A MARINE DEPOSIT.. ..MINERAL 

 ORIGIN. ...FLOATING ISLANDS.. ..A RECENT VEGETABLE SUB- 

 STANCE. 



ALTHOUGH I encourage the hope, that the circumstances adduced 

 are such as will be likely to be successful, in establishing the opi- 

 nions I have offered, respecting the origin and nature of this sub- 

 stance ; yet something more remains to be done. The opinions 

 already advanced, on this subject, have a claim upon our attention ; 

 and although the greater part of them may not require a formal 

 refutation, others will require to be examined, that it may be de- 

 termined whether they offer a satisfactory explanation of the pro- 

 perties which are possessed by this substance. It is likewise incum- 

 bent to determine whether those particular circumstances, which 

 have been supposed most powerfully to support the hypotheses 

 which have been already advanced, militate against, or favour, 

 that which is here attempted to be established. 



The first opinion 1 shall notice is that which supposes peat to 

 have existed, in its present form and state, from the creation of the 

 world. In opposition to this opinion it must be sufficient to ob- 

 serve, that peat is composed of substances which bear the indu- 

 bitable marks of having existed in another state ; also that there 

 is an abundance of instances of its formation going on, even at 

 the present day. 



The hypothesis, which supposes it to have been formed by a bitu- 

 minous deposit from the waters of the sea, must be rejected, from 

 its being impossible thus to account for the prodigious quantity 



