600 STEVENSON— FORMATION OF COAL BEDS. [November 3, 



peninsula. Algal lake, now covering only a few acres, is surrounded 

 by a great wooded swamp, extending northeastward to a large lake 

 and coming down almost to the water at the north end of Algal lake. 

 The swamp loosestrife {Dccodon vcrticillatus) forms the marginal 

 zone. The bottom of the lake is covered with soft flocculent ooze, 

 composed of unicellular alg?e with diatoms as well as pollen from 

 conifers. Davis conceived that peat of this type would be like 

 cannel and he thinks that freshwater algae may have been more 

 abundant in Carboniferous times, when all types of plant life were 

 lower than now. A similar material was found in a mature bog, 

 where the section is 



Feet. 



1. Coarse peat, with stumps, roots and fallen stems 5 



2. Brown peat, good texture, quite plastic 5 



3. Soft, light-colored peat, like that at Alga! lake 4 



These are the only localities in the United States whence this type 

 of peat has been reported. Ehrenberg, Friih and Potonie have de- 

 scribed the felt or Meteorpapier, as Ehrenberg termed it, which 

 remains on swamps after floodwaters have been drained ofif. Potonie 

 calls it Sapropel carpet, and he has given a photograph showing the 

 material covering land plants of a swamp. But the phenomenon is 

 of by no means rare occurrence in the eastern part of the United 

 vStates. Davis has communicated by letter that he saw it in 1910 

 near St. Augustine in Florida, where the water of a swamp had 

 been lowered ; the felt was conspicuous on the tussocks, etc. In the 

 Everglades of the same state, he found the felt about the grass and 

 sedge stems in the level swamps. Here and there it contained a 

 considerable quantity of calcareous matter, due perhaps to activities 

 of Cyaphanacese present in the algal association. The same type of 

 felt-like development is seen during springtime in marshes of the 

 northern states, where the water drains ofif slowly. Spirogyra and 

 other filamentous alga? sometimes cover the temporary ponds and 

 are left as a felt-like cover when the water has been withdrawn. 

 This felt breaks into small pieces as it dries and is added to the peat. 

 The writer has observed it in very small patches on the New Jersey 

 marshes; he has seen patches more than lo feet square at many 



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