PEAT. 339 



such as the Potamogetons, that subside after flow- 

 ering, to form a vegetable stratum, which receives 

 constant additions from the Scirpus, Lobelia, Subu- 

 laria, and others, destined, in another way, to the 

 same office. These also, detaining sand and clay, 

 gradually shoal the margins, so as to give a place 

 to the semi-aquatic plants, bulrushes, reeds, and 

 others, which, advancing from the edge, gradually 

 generate a marsh, so as to form a place for a third 

 class, till the process of solidification is completed. 

 If, at other times, this last operation alone takes 

 place, the final result is, in any case, the forma- 

 tion of lake peat, passing into that of marshes ; and 

 thus finally producing those extensive flat bogs, the 

 nature and origin of which have been so much mis- 

 apprehended by naturalists as well as agriculturists. 

 I need not have noticed this error, but from its prac- 

 tical importance to the latter ; negligent, or ignorant, 

 of that in which they are often so deeply concerned. 

 It is under this peat that shell marl occurs, as it is 

 also the evidence of former lakes, or pools; and a geo- 

 .logical eye will generally detect the places of these, 

 however long solidified, as the agriculturist may now 

 learn to do the same : and had the origin of peat been 

 as well understood as it has been largely discussed, 

 this valuable manure would not be the rare and acci- 

 dental discovery which it now is. 



The next division is that of Forest peat, including 

 submerged wood ; while if some writers have as- 

 signed this origin to all peat, no other answer than 

 the present history is necessary. And in every case 

 of this nature, the far larger portion is produced by 

 plants subsequent to the fall of the forest, so as to be, 

 in reality, a marsh peat ; as, further, this is continu- 

 ally forming in moist woods, from the fallen leaves 



z 2 



