IMPORTANT TYPES OF PEAT MATERIAL. 29^ 



The material disintegrates rather poorly and becomes brittle when 

 overdraincd, breaking down into a dust, or mull. Older laj^ers are 

 blackish in color and appear more or less structureless. 



The type is more generally a transition feature to the hog group 

 of peat materials; it is found in peat deposits in the Northwestern 

 States and seems to occur there in considerable thicknesses. In the 

 Central and Eastern States it is found only in layers and pockets of 

 irregular size, heavily admixed with the plant remains of species of 

 Carex, Phragmites, and other peat-forming plants. Tables I and II 

 contain the more important physical and chemical data for this type 

 of peat. 



THE BOG GROUP OF PEAT MATERIALS. 



Types of peat material (autochthonous) from bog-meadow and 

 bog-shrub stages of a vegetation series in wet places, with the water 

 table near or slightly below but rarely above the surface. 



The plant remains are characteristically spongy and porous or 

 matted-fibrous to wickerlike peat, somewhat resistant to disintegra- 

 tion, reddish, yellowish, and deep brown in color. The interstices are 

 filled with a macerated debris in varying proportions, often soft and 

 oozelike, in which fragments of cell complexes are usually well 

 enough preserved to be determinable. The resinous constituents and 

 the threadlike rustj^ brown root fragments of heaths with mycelial 

 fungi are an important factor in lending the specific character and 

 value to this group. In transition stages the finer debris or ground 

 mass forms a considerable portion of the material, with intergrada- 

 tions from structureless plastic-appearing substances discerned with 

 difficulty to clearly recognizable fibrous and woody fragments. 



The materials are derived from vegetation units which appear first 

 as scattered, more or less localized plant associations in the marsh 

 stages of a peat deposit. It seems that the succession of marsh to 

 bog has taken place far more frequently than recognized hitherto, 

 since sections through the profile of the low^er layers of x^eat deposits 

 in many localities show clear evidence that the area was formerly 

 occupied by marsh vegetation. Quite similar stratigraphic succes- 

 sions leading from marsh to bog recorded in the peat deposits of 

 European moors have been recognized in this country. In lacustrine 

 deposits, however, bog vegetation appears often as foreland com- 

 munities and immediately following the semiaquatic stages of a vege- 

 tation series after the accumulation of macerated, structureless, water- 

 formed peat has reached nearly to the water level. B}^ means of 

 much-branched interwoven underground stems and fibrous rootlets 

 they border open water or completely surround it as a floating mat, 

 which rises and falls with the seasonal variations in the water table 



