14 BULLETIE" 802, IT. S. DEPARTMEIsTT OY AGKICULTURE. 



with crops for the purpose of operating the peat deposits at their 

 maximum efficiency. Lack of knowledge of the efforts made along 

 these lines by European workers over a period of more than a century 

 is directly responsible for the failure wliich the attempts in this 

 country have met. 



A TENTATIVE CLASSIFICATION OF IMPORTANT TYPES OF PEAT 



MATERIALS. 



In the following classification of peat materials all those data of a 

 physical and chemical nature resulting from investigations of Euro- 

 pean types of peat have been summarized in Tables I and II which, 

 in the opinion of the writer, may safely be applied to the correspond- 

 ing types of plant remains found to occur in the peat deposits of the 

 Lake belt, e. g., Ohio (5) and the New England States, e. g.., Massa- 

 chusetts (7), and present also in other States within the glaciated 

 area of North America. For purposes of microscopic identification 

 of plant remains the illustrations given in Friih and Schroter (10) 

 afford an excellent basis for analysis and comparison. 



THE AQUATIC GROUP OF PEAT MATERIALS. 



Types of peat material (allochthonous) from open water and from 

 shore stages of a vegetation series, of which the plant remains accu- 

 mulated below the water level. 



The peat materials are structureless or coarsely macerated, soft, or 

 compact and sticky, especially in older and deeper strata. Thej vary 

 in composition, texture, color, etc., according to the depth of water 

 and the character of the water in the initial stages of the area or of 

 the vegetation series ; they are largely, though not wholly, composed 

 of the more resistant residues of plant remains, bits of woody and 

 fibrous material, fragments of root and shoot tissue, the outer coats 

 of cellular organisms, and a finely macerated debris as an embedding 

 or binding ground mass which has either partly or wholly lost all 

 vestige of its original organic structure. To this is added in various 

 proportions and from various sources material of plant and animal 

 origin, as well as dust, silt, etc., from the surrounding area, laid down 

 by wind and current. 



Several distinct vegetation units which grow either free floating, 

 wholly submerged, or rooted and partly submerged in water may 

 form at any level considerable and extensive layers of material 

 by the constant accretion of plant remains. These peat-forming 

 plants are represented to-day by a great number of species and in- 

 dividuals with semiaquatic habits of growth in fresh and brackish 

 water. Among them are species of Ceratophjdlum, Potamogeton, 

 Castalia, Nymphaea, Peltandra, Pontederia, Polygonum, Decodon, 



