34 BULLETIN 802, V. S. DEPAETMENT OF AGRICULTURE. 



' BOG-SHRUB TYPE. 



"Heath peat," " Reisertorf," " Heidetorf." 



Reddish to rusty brown wickerlike peat material, partly finely 

 fibrous from rootlets, but with numerous small twigs forming a 

 prominent proportion. The woody fragments are derived from roots, 

 stems, and branches of various bog shrubs, mainly heaths; the mac- 

 erated ground mass is more or less resinous. 



The type is often accompanied by a marked occurrence of highly 

 ferruginous impurities either distributed through the mineral sub- 

 soil as a hard impermeable layer or pan or in the form of bog iron 

 on and near the surface. In coastal climates the bog shrubs show 

 beneath the peat material a layer of leached-out whitish or gray 

 sand of varying thickness; underlying it is a characteristic blackish 

 or yellow to rusty brown iron-stained sand, which often contains 

 much of the mineral material and organic colloidal complexes leached 

 from the upper sandy layer. The soils when denuded of their 

 surface covering of peat material appear to be unsuitable for ordi- 

 nary farming practices unless well handled. Pans, however, are by 

 no means confined to heath bogs ; they often occur in forests and on 

 certain marshy and cultivated sandy soils. 



The plant remains in heath peat are derived largely from bog 

 shrubs, SLimong vfhich Andromeda sp. and Cassandra {Chamaedaphne) 

 sp. are the most prominent of the ericaceous plants. Other genera, 

 such as Ledum, Vaccinium, Myrica, and Kalmia, are less numerous in 

 individuals and not so general in their distribution as to give rise to 

 specific tj^pes of heath peat. In some of the sphagnum-cranberry bog 

 meadows they are present in sufficient numbers to make a dense 

 thicket, thus shading and even destroying the vegetation which 

 covers the ground. The plants spread rapidly by means of long 

 horizontal underground stems, from which arise at intervals erect 

 leafy branches. 



Empetrum nigrum and Call/wna vulgaris occur very rarely on bogs 

 in the United States, but they are among the low evergreen heath 

 shrubs in the bogs of Canada and occur generally on the bogs or 

 high moors of northern European peat deposits. 



The chemical and other data cited in Tables I and II relate to 

 heath types of peat on high moors. 



THE SWAMP GROUP OF PEAT MATERIALS. 



Types of peat material from coniferous trees and from deciduous 

 shrub and tree stages of a vegetation series on a wet substratum with 

 the ground-water table generally below the surface during part of 

 the year, as in bog forests and pond swamps, or partially submerged, 

 as in river and coastal swamps. 



