FORMATION OF BOGS. 29 



fallen trees in producing bogs, and of smaller animals, insectSj 

 and birds, in destroying the woods.* / 



Bogs generally originate in the cheeking of watercourses by [ 

 the falling of timber or of earth and rocks, or by artificial ob- j 

 structions across their channels. If the impediment is sufficient 

 to retain a permanent accumulation of water behind it, the trees 

 whose roots are overflowed soon perish, and then by their fall 

 increase the obstruction, and, of course, occasion a still wider 

 spread of the stagnating stream. This process goes on until the 

 water finds a new outlet, at a higher level, not hable to similar 

 interruption. The fallen trees not completely covered by water 

 are soon overgrown with mosses ; aquatic and semi-aquatic plants 

 propagate themselves, and spread until they more or less com- 

 pletely fill up the space occupied by the water, and the surface 



quantity of firewood yielded by the forests of New England to the acre is 100 

 cords solid measure, or 474 cubic yards ; but this comprises only the trunks 

 and larger branches. If we add the small branches and twigs, it is possible 

 that 600 cubic yards might, in some cases, be cut on an acre. This is only 

 one-eightieth part of the quantity of peat sometimes found on the same area. 

 It is true that a yard of peat and a yard of wood are not the equivalents of 

 each other, but the fuel on an acre of deep peat is worth much more than that 

 on an acre of the best woodland. Besides this, wood is perishable, and the quan- 

 tity on an acre can not be increased beyond the amount just stated ; peat is 

 indestructible, and the beds are always growing. See post. Chap. IV. Cold 

 favors the conversion of aquatic vegetables into peat. AsbjSrnsen says some 

 of the best peat he has met with is from a bog which is frozen for forty weeks 

 in the year. 



The Greeks and Romans were not acquainted with the employment of peat 

 as fuel, but it appears from a curious passage which I have already cited from 

 Pliny, N. H., book xvi., chap. 1, that the inhabitants of the North Sea coast 

 used what is called kneaded turf in his time. This is the finer and more thor- 

 oughly decomposed matter lying at the bottom of the peat, kneaded by the 

 hands, formed into small blocks and dried. It is still prepared in precisely 

 the same way by the poorer inhabitants of those shores. 



But though the Low German tribes, including probably the Anglo-Saxons, 

 have used peat as fuel from time immemorial, it appears not to have been known 

 to the High Germans until a recent period. At least, I can find neither in Old 

 nor in Middle High German lexicons and glossaries any word signifying peat. 

 Zurb indeed is found in Graff as an Old High German word, but only in the 

 sense of grass-turf, or greensward. Peat bogs of vast extent occur in many 

 High German localities, but the former abundance of wood in the same regions 

 rendered the use of peat unnecessary. 



* See Chapter II., post. 



(^^ 



