62 STEVENSON— INTERRELATIONS OF THE FOSSIL FUELS. 



peat already formed and adds to the mass. As soon as local or 

 general conditions again become favorable, peat growth in the ordi- 

 nary way would be resumed and the invading vegetation would be 

 killed. The record of alternating wet and dry periods is distinct in 

 very many deposits which offer no evidence of serious waste during 

 the passage from one to the other. Some of the less moist periods 

 must have continued for centuries, if one may judge from the age 

 of rooted trees in the forest layers. Certainly the desiccation 

 process did not extend deeply, for the roots of trees in those layers 

 are spread horizontally in shallow depth, as though avoiding the wet 

 peat below, just as do the roots of the invading forest trees now. 



It is wholly possible that comparatively little of the peat now 

 forming will reach a later stage in transformation ; the agricultural 

 importance of peaty lands is understood, as is also the method for 

 their preservation, so that the work of drainage and reclamation will 

 be more and more extensive in the future. But with that this study 

 is not concerned. The questions involved deal with conditions 

 prior to man's interference with nature's operations. The evidence 

 all encourages the belief that a very great part of the older peat has 

 been protected and that the peat now forming in uninhabited regions 

 will be protected in like manner, to become a genuinely fossil fuel. 

 Buried peat deposits are known throughout the world. 



Forchhammer, Jentzsch, F. E. Geinitz and others have described 

 dune-covered bogs along the Baltic shores and C. A. Davis has re- 

 ferred to the same condition in IMichigan. The process continues in 

 those regions. One finds frequent notes respecting submerged 

 bogs, often continuous with living bogs on the shore, as though the 

 swamp had advanced up the surface during the subsidence. In 

 some localities, portions of the submerged bog are already covered 

 with materials from the land, while other portions are still free from 

 cover ; in such cases, the overlying deposit should contain marine 

 forms. At times, the influx of inorganic matter continues until 

 land conditions, have been restored and the peat extends over the 

 new surface. Borings in northwestern Europe pass through a suc- 

 cession of peat bogs separated by sand or clay. Similar relations 

 are exposed in deep excavations and occasionally in uplifted areas. 



