28 NEW YORK STATE MUSEUM 



Cleaveland in his mineralogy^ distinguishes between (1) fibrous 

 peat, or turf, and (2) compact peat, or peat proper. His defini- 

 tion and description of peat are so good that I quote them in 

 full. 



Peat consists essentially of vegetable matter in various states 

 of decomposition ; but is more or less mixed with earths and salts. 

 It appears to differ from vegetable earth [or mold] by retaining 

 nearly all the principles of the vegetable, though these principles 

 may have formed combinations which did not exist in the living 

 plant. 



We notice two varieties of peat, depending chiefly on the degree 

 of decomposition in the vegetable. (1) Fibrous peat. This 

 variety, sometimes called turf, is composed chiefly of vegetable 

 fibers, variously interlaced, and united by a slimy, vegetable mat- 

 ter in a more advanced state of decomposition. Its texture is of 

 course very loose. Hence we perceive the roots, stems and leaves 

 of various plants, which grow in swamps, bogs, marshes or heaths; 

 indeed, it sometimes seems to be composed almost entirely of 

 leaves. When dry, it is lighter and more elastic than compact 

 peat, and its color is usually less dark. (2) Compact peat. When 

 recently dug, it forms a very slimy mass, soft to the touch, and 

 sufficiently tenacious to be cut OT molded into small regular solids, 

 like a brick. When dry, its texture becomes more or less firm and 

 compact, and it exhibits an earthy fracture. It is harder, heavier 

 and blacker than the first variety. It embraces few or no visible 

 remains of the organic parts of vegetables and seems to have orig- 

 inated chiefly from aquatic plants. In some rare instances its 

 fracture is glossy like resin. 



The two preceding varieties pass insensibly into each other and 

 frequently occur in the same bed. In this case, the upper part of 

 the bed is loose and fibrous, having undergone only partial decom- 

 position ; but, on approaching the lower parts, the remains of the 

 vegetable fiber gradually disappear, and the peat becomes more 

 compact, in consequence of the more complete decomposition of 

 the vegetable and of the pressure of the superincumbent mass. 



Process of peat formation 



The manner in which a peat bog is formed has been described 



under the head of lake swamps, but the process of peat formation is 



a subject for theories. It is known that the vegetable matter loses 



certain percentages of carbon, hydrogen and oxygen, but just what 



^Cleaveland, P. Elementary Treatise of Mineralogy and Geology. 1822. 



