IMPORTANT TYPES OF PEAT MATERIAL. 13 
and technical utilization, should therefore be attached to the profile 
structure of a peat deposit and to the climatic and geologic differences 
of peat-lane} areas. 
The arrangement of types and groups of peat material given be- 
low is, it should be repeated, a tentative one. It is presented partly 
from an ecologic point of view and deals, therefore, with a series of 
peat- forming vegetation units within a set of field conditions such 
as the writer has described elsewhere for Ohio (5) and Massachu- 
setts (7). 
The outstanding physical relationship is the water content of the 
initial area and its effect upon the character of the series of vegeta- 
tion stages forming peat and upon the manner of accumulation of 
plant remains. This fact is of the greatest importance also from 
an economic point of view in connection with the improvements to 
be given a peat-land area. It may be accepted as an axiom that 
undrained deposits of peat contain about 70 to 95 per cent of water, 
which should not be reduced to less than 65 per cent if the area is 
to be used for agricultural crops. Drainage and desiccation of peat 
materials below 60 per cent of water content have been observed to 
decrease their capacity for disintegration and weathering. The 
fibrous organic material becomes brittle, inert, maintains its initial 
appearance for considerable periods of time, and does not become 
readily nitrified. Certain of the macerated and water-formed types 
of peat become hard and compact and are not easily penetrated by 
the roots of crop plants or by water and air. On the other hand, 
the dewatering of peat materials, especially the macerated types 
and the well-disintegrated phases of other types, to a water content 
of approximately 25 to 30 per cent is an essential requirement be- 
fore they can be used for technical purposes. Desiccation is one of 
the outstanding problems in connection with the manufacture of 
peat into a finished product. Thus far, the employment of pressure 
or of drying other than by the natural action of sun, air, and wind 
has not proved economically feasible. 
It is obvious, therefore, that the utilization of peat deposits for 
agriculture, for manufacturing purposes, or for a combination of 
both implies operations which appear in some degree antagonistic. 
They have been harmonized, however, but only through investigations 
which give information concerning the quality and quantity of peat 
materials, the conditions of their formation, and the methods of 
development required before they can be made available sources of 
food, power, or finished products. On the continent of Europe in- 
dustries which are dependent on peat materials for these purposes 
have been centralized and located in the vicinity of selected deposits 
situated conveniently with respect to cheap water transportation. 
Provision is made for contemporaneous and subsequent cultivation 
