IMPOKTANT TYPES OP PEAT MATEKIAL. 37 
corporated in a more or less disintegrated leaf mold, which contains 
also the remains of herbaceous forms, ferns, and other vegetation 
growing in a mature hardwood forest. The older material of the 
layer is usually brownish black, § woody , granular, with an abund- 
ance of fungal hyphaa. This debris characterizes the more fertile 
area, a large proportion of which is often brought under cultivation 
with a small expenditure for fertilizers on account of the finer tex- 
ture of the well-weathered material and its aerated condition. 
The types of most frequent recurrence but which at present must 
remain without further characterization are the maple-ash-elm 
(Acer-Fraxinus-Ulmus) type in swamps and bogs of the Central 
and Northeastern States, often associated with oak (Quercus spp.) 
and basswood (Tilia sp.) or with conifers, and the gum-maple 
(Nyssa-Acer) type in the swamps of the Southeastern States. The 
data in Table I serve to show the relative value of the European type 
of deciduous- forest peat. 
CONIFEROUS-FOREST TYPES. 
" Fohrenwaldtorf.'' 
Reddish brown plant parts from evergreen trees or from a mixed 
stand of conifers and deciduous forest trees which differ much in 
their resistance to weathering and decay agencies. The proportion 
of fibrous or leafy material and of weathered products from shrubs 
and herbs is quite variable. The ground mass in which the more 
resistant components are embedded is soft, plastic, and under mode- 
rate draining conditions becomes granular rather slowly. In over- 
drained deposits it dries and shrinks greatly and frequently takes 
on the consistency of a compact substance, impervious to water, espe- 
cially when resinous material comprises an important element in the 
woody components. Experience indicates that coniferous peat ma- 
terials are likely to be of low value for intensive farming purposes, 
even several years after clearing. 
For each geographical or climatic district there are usually repre- 
sentative tree species which establish themselves, first scattered, then 
in a zone near the shore of lakes or valley channels, and eventually 
cover the entire peat-land area. As they grow taller they intercept 
a large amount of light and thus eliminate and displace the herba- 
ceous and even shrubby undergrowth. The water of a heavy rain- 
fall is held back sometimes to a considerable depth by the dense 
growth and tangle of fallen vegetation, thus extending the swamp 
conditions over adjoining areas. The larger number of trees have a 
shallow superficial root system, which may be removed by various 
methods of clearing, such as brushing, blasting, pulling, or burning. 
The plan of " brushing out " the land, plowing shallow the first time, 
gradually increasing the plowed depth from year to year, and seed- 
