IMPORTANT TYPES OF PEAT MATERIAL. 33 
Except in a few Northern States and in Canada the built-up layers 
of bog-moss peat are rarely of great thickness or purity in plant 
composition. Other peat-forming plants which usually accompany 
sphagnum mosses are the cranberry {Y accinium spp.), sundew 
(Drosera spp.) , arrow grass {Scheuchzeria sp.) , cotton grass {Erioph- 
orum spp.), Rynchospora spp., Meny writhes sp., various species of 
sedge (Carex), and others (5). 
The rarity of sphagnum peat is noteworthy and, together with 
the rather restricted occurrence at the present day of " moss " bogs 
as compared with sedge or "grass" bogs and "heath" bogs, is in- 
teresting, since sphagnum mosses are by many considered to be the 
starting point and the type plant association of peat deposits. 
Considerable work has been done upon the physical and chemical 
features of this type of peat material, some of which has been sum- 
marized in Tables I and II. Other correlative phenomena have 
■been discussed in a previous publication (5, p. 386-392). 
ARROW-GRASS TYPE. 
" Scheuchzeria peat," " Beisentorf." 
COTTON-GRASS TYPE. 
" Eriophorum peat," " Wollgrasstorf." 
These two types are generally a composite in the peat accumu- 
lations of this country. The plant remains appear to be rarely 
of the thickness of accumulation or homogeneity in composition 
recorded for European deposits. They are derived from bog plants 
which associate with or follow closely a zone of the sphagnum-cran- 
berry stage of bogs in our northern peat deposits. 
The peat material is rusty to reddish brown, rather coarsely 
fibrous from plant remains, such as roots, rootlets, leaf bases, and 
leaf fibers of the wool or cotton grass {Eriophomim spp.) and of the 
arrow grass {Scheuchzeria sp.), roughish from the clustering of 
culms, with varying admixtures of the grayish to dark-brown par- 
tially disintegrated sphagnum mosses and the finely threadlike 
material from cranberry and similar heaths. 
The coarser fibered Eriophorum component is quite resistant to 
disintegration and to cutting processes. When relatively pure in com- 
position Eriophorum peat is deemed of considerable value for textile 
purposes, the manufacture of cloth, and similar technical uses. 
The type of material in which the plant remains from arrow grass 
preponderate consists of a reddish finely fibrous network of rootlets 
inclosing thin scalelike leaves and leaf bases of this plant; the peat 
material is inclined to be brittle when dry and breaks down into mull 
or peat dust. Chemical and other data are given in Tables I and II. 
