J9II-] STEVEXSOX— FORMATION OF COAL BEDS. 609 



at tlie bottom, a considerable portion is formed of barks, wood, 

 leaves and other debris, transported and deposited in the water. 

 Roots can be seen penetrating the gray clay on which the deposit 

 rests. On the borders, the peat has not been changed in position 

 and it is felted and herbaceous. In one part it seems to be composed 

 exclusively of transported plants, there being barks of flattened 

 birches ; some laminated portions are formed of humefied epidermis 

 material. 



No reasons are given for assigning a great portion of the mass 

 to transported material, the matter being taken apparently as beyond 

 dispute ; but one may surmise that the presence of stumps rooted in 

 the peat, the prostrate trunks and the fragmentary condition of the 

 enclosing material ma}- have been for him convincing. Grand' Eury 

 did not believe that trees would grow in peat and the fragmentary 

 condition of plant remains was proof that they had been washed in. 

 The conditions, described by him, are precisely those which are 

 familiar in bogs, for which no conception of transport is admissible. 



The Danish swamps were studied by Steenstrup^-- long ago ; his 

 grouping resembles that employed by the German students. The 

 most important is the \\^aldmoor or Skovmose type occupying de- 

 pressions in Quaternary deposits, often more than 30 feet deep. 

 Where the area was small, the sides were abrupt and the trees 

 growing on them eventually fell into the bog. where they have been 

 preserved. In depressions of great extent, one finds an exterior 

 wooded zone surrounding an interior or central bog zone. The 

 latter resembles the Lyngmose, the heather or Hochmoor stage. 



The central area of the Skovmose is very regular. It rests on 

 clay derived from the borders ; above which one finds ordinarily one 

 and a half to even four feet of amorphous peat, becoming pulpy in 

 water and containing indeterminable plant remains. The peat is 

 very pure in normal bogs, but layers of calcareous or silicious matter 

 are not unknown. A layer of hypnum-peat rests on the amorphous 

 deposit, 3 to 4 feet thick, containing Finns sylvestris, which grew on 

 the spot, at times forming a forest on the swamp. The trees were 



^" Steenstrup, as summarized by Morlot, Trans, in Ann. Rep. Smithsonian 

 Inst., Washington, 1861, pp. 304 et seq. 



207 



