STEVENSON— INTERRELATIONS OF THE FOSSIL FUELS. 41 



tion of trees on a forested moor and bring about return of the peat 

 moss condition. 



Pokorny,"^ after exhaustive study of the Hungarian moors, pre- 

 sented a classification of the deposits and described the stages of 

 growth. He recognized two general types, Hochmoors and Flach- 

 moors, equivalent to the supra-aquatic and infra-aquatic of Les- 

 quereux. The former include both forested and Sphagnum moors 

 and are confined to higher land, while the Flachmoors, of many sorts 

 and with many names, are on lower land and have an approximately 

 level surface, contrasting with the convex surface of Hochmoors. 

 The successive stages in growth of the Flachmoor are Hydrophyton, 

 Rohrwald, Rohrwiese, Wiesen, Moorwiese, which correspond to those 

 indicated by observers already cited. It is not necessary to make 

 citations from the works by Rennie, Steenstrup, Senft or others of 

 the earlier investigators in northern Europe, for their conclusions 

 dififer in wholly unimportant details from those of the later students. 

 It is certain that the successive stages in development of a peat de- 

 posit were recognized more than three fourths of a century ago ; since 

 that time, the scheme has been modified only in detail. 



In 1910, Potonie, using the JMemel delta moor as the illustration, 

 summarized the stages thus, in descending order : 



Sea-climate Hochmoor, 

 Hochmoor, -\ Hochmoor Vorzone, in part with Arundo 

 phragmites. 



Conifer inner forest zone, 



P)irch zone. 



Alder moors. 



Reeds and rushes, shore zone, 

 Sapropel deposits. 



In a Hochmoor under a land climate, where the rainfall is less, 

 the succession is completed by a heath stage, during which plants of 

 the heath family take possession of the surface. This, Potonie sug- 

 gests, may be regarded as the expiring stage of peat growth. If a 

 boring were made through the Hochmoor and underlying materials 



29 A. Pokorny, " Untersuchungen iiber die Torfmoores Ungarns," Site. 

 Akad. JViss. IVicn. Bd. XLIII, Abt. I., 1861, pp. 59-65, 86. 



Zwischenmoor, 

 Flachmoor, 



