STEVENSON— INTERRELATIONS OF THE FOSSIL FUELS. 31 



and forests of birch and aspen. Beyond the Ob, the road passes for 

 about 50 miles through a marshy forest of pines and firs, which 

 extends from near Tomsk southward for more than 300 miles almost 

 to the head of the Kia River. In the area west from Lake Baikal, 

 within the drainage area of the Yenisei, there are impassable marshes 

 of vast extent, sometimes forested — the Taiga. This condition 

 exists between the Kau and Oka Rivers and northward to the An- 

 gara. Beyond Lake Baikal, broad valleys hold great marshes covered 

 with vegetation throughout and conifers are abundant in such locali- 

 ties. East from the Yablonovy mountains, the Taiga is characteristic 

 of moist area ; pines, firs and black birches are the common forms. 



True peat is present in localities where the required conditions 

 appear to be wanting. The so-called forest peat has accumulated to 

 a thickness of several feet in many places within the Rocky Moun- 

 tain region, the material being merely ofl:"al from dense forests of 

 giant firs. In northern New England, one often sees the surface in 

 railroad cuts more or less covered with moss-peat, though the rock 

 is a gravelly sand. This is wholly similar to the Rohhumus, seen so 

 commonly on rock surfaces within forests of both Europe and North 

 America. But the needed conditions are here, though not sufficient 

 to encourage rapid growth. The offal from the trees is abundant and 

 retentive of water, while the moss, once saturated, parts very slowly 

 with its moisture. 



Extent of Peat Deposits. — As already stated, a peat deposit may 



cover only a few square feet or it may cover an area of hundreds 



even thousands of square miles. The subtropical Everglades of 



Florida embrace not far from 7,000 square miles; the partly living, 



partly buried peat of Holland, Belgium and north France has nearly 



as great extent, as shown by Lorie. Russell's exploration of Alaska 



led him to assert that peat covers not only the vast tundra but also 



most of the wooded region as well as of the river plains. The buried 



deposit of the Ganges delta has been found in numerous borings 



within a space of more than 2,500 square miles. Skertchly has shown 



that in the Fenland of England the peat is practically continuous 



throughout 1,800 square miles. ^' Great areas exist on the north 



1" R. M. Harper. "Preliminary Report on Peat Deposits of Florida." 1910; 

 J. Lorie, " Les dunes interieures, les tourbieres basses et les oscillations du 



