639 



PEAT. 



ALTHOUGH peat does not in every instance lie 

 above all the alluvial soils which may be present, 

 that is at least its predominant position. It is 

 invariably found above those of an extensive and 

 general nature which may be referred to a dilu- 

 vian cause ; and, where it lies beneath deposits of 

 clay or sand, these will be found of modern 

 origin, and produced by the very recent action 

 of rivers. 



These alternations are not frequent where 

 they do occur ; and they consist either of marie 

 or sand, deposited in lakes, or of clay and sand 

 formed at the estuaries of rivers. The beds of 

 peat, in these instances, are generally of incon- 

 siderable thickness. Where it is found, as is 

 most frequently the case, at the surface, it lies 

 above the ordinary alluvial soil ; forming strata, or 

 tracts, more or less extensive, according to the 



