IMPORTANT TYPES OF PEAT MATERIAL. 
saline impurities and in acid, alkaline, or neutral reaction. Some of 
these rock formations yield marked amounts of soluble injurious salts. 
Special climatic conditions influence appreciably the disinte- 
gration of peat materials, the formation of organic colloidal debris, 
and the direction of movement or transport of dissolved mineral 
constituents (8). The reactions may lower the supply and concen- 
tration of nearly all available essential plant-food constituents and 
thus effect malnutrition, a prevalence of plant diseases, and allow 
certain plants and microorganisms to outgrow others, or they may 
lead to local accumulations of salts at the surface of the peat deposit 
or at the margins and in the mineral substratum underneath peat 
accumulations. Cultural practices and drainage systems in no small 
measure may favor and accentuate both the contamination through 
the movement of underground waters or springs in peat materials 
with high decay capacity and the concentration of salts by seepage or 
by evaporation. More consequential still are the effects of a pro- 
nounced inland or a typical oceanic climate on the disintegration, 
absorption, deposition, and leaching phenomena. Aside from the 
presence of either an abundance or a deficiency of agriculturally de- 
sirable mineral constituents, the climatic contrasts give rise to classes 
of peat land which resemble closely the ." Tschernosem " and the 
" Podsol " condition featured by foreign writers (11). 
It is obvious, therefore, that those inquiries are likely to be most 
fruitful which are concentrated first of all on the fundamental prob- 
lem of determining and characterizing the types of peat material 
which are representative of distinct regional divisions or geographic 
areas of the United States and reserve for later discussion the details 
of the structure and contents of special peat deposits which are con- 
sidered to be either with or without great value or are selected as 
representative peat deposits for specific experimental or industrial 
purposes. 
It seems to the writer eminently desirable at this time to give con- 
sideration especially to those chief types of peat material in this 
country which are characteristic of peat deposits in European coun- 
tries; to emphasize mainly the grades or types which resemble or 
coincide with each other and whose botanical composition is based 
upon the remains of plants known to occur in Europe; and to 
characterize those phases which are preserved conspicuously in a 
similar stage of disintegration in this country, irrespective of their 
positional relationship in the different layers of a peat deposit. They 
alone demand consideration in the present state of our imperfect 
knowledge, partly because through the recognition of these types 
considerable progress can be made in the fixing of standards of qual- 
ity and in securing their adoption; largely, however, because the 
physical and chemical characteristics of these types have been sys- 
