118 



Scientific Geology. 



acter : for my opportunities of observation on this subject have been 

 but few. 



Geologists are not a little perplexed, satisfactorily to account for sub- 

 marine forests. Some of them, it has been thought, might have re- 

 sulted from the breaking of the barrier of a peat swamp by the ocean ; 

 whereby it was drained and the soil rendered more compact so as to 

 subside below the level of the ocean. But in general it has been sup- 

 posed that these forests have subsided in consequence of earthquakes, 

 or other internal movements of the earth. But if it should be found, 

 as there seems reason for believing, that they exist in every quarter 

 of the globe, and at nearly the same depth beneath the ocean, a 

 cause (like those just named) which is local and irregular in its ope- 

 ration, will hardly explain their occurrence. 



Peat. 



Various causes are in operation to produce an accumulation of 

 mud upon the bottoms of ponds, lakes, estuaries, &c. In this mud 

 various aquatic plants will take root, and by their decay will swell 

 the deposit. At length the pulpy mass nearly reaches the surface, 

 when sphagneous and other mosses take root in it, along with numer- 

 ous other plants, and by their gradual decomposition the pond or the 

 lake becomes converted, in the course of ages, into a swamp or marsh. 

 On digging into it, the bottom will be found to consist, near the sur- 

 face, of interlaced vegetable fibres and roots, with only a small por- 

 tion of earth : farther down the vegetable matter will be found more 

 decayed and compact, until at length, in many instances, perfect 

 compact peat, with occasional layers of mud, will be discovered. 



This is the simple and summary account of the origin of the differ- 

 ent varieties of peat. And since the process is daily progressing, it 

 is properly an alluvial formation : though probably a part of the peat 

 in this state was produced previous to some of the latest general and 

 important changes which the earth has undergone. According to 

 this statement, almost any vegetable matters, that have remained for 

 some time beneath the surface of the soil, may be called peat ; and it 

 may even be produced beneath the sea by marine plants, such as the 

 Zostera marina. It is only within certain limits of moisture and tem- 

 perature, however, that proper peat can be produced : and hence in 

 the torrid zone, the decomposition is so rapid and perfect, that peat is 

 rarely found. Hence, too, in northern latitudes, the most elevated 

 swamps are the most favorable spots for its production : that is, for 



