I9II-] STEVEXSOX— FORMATION OF COAL BEDS. 39 



uted materially to the formation of coal and, at a later date, Bischofif 

 conceived that the Sargasso sea might yield a coal bed. Mohr/^ 

 in 1866, presented this view with great energ>-, and his opinions 

 received more or less support from some eminent students. 



Mohr contrasts stone- and browncoal. the one being fusible the 

 other infusible. Land plants with much woody fiber yield charcoal, 

 which soon decays when exposed to air and moisture. But sea- 

 weeds, river and lake algse, having no fiber, decay to slime, which 

 hardens through loss of COo and CH^ the original composition being 

 that of starch and the allied substances. He combats Bischoff's 

 assertion that Calamites and other land plants were concerned in 

 forming coal, for the mass of the coal is amorphous and no treat- 

 ment gives trace of plant skeleton. Evidently, everything with rec- 

 ognizable structure is a foreign body. Coal did not originate from 

 land plants but from water plants, whose growth is protected from 

 air and decay. 



Only one of these water plants, a grass of wide distribution, is 

 a phaenerogam ; the genera and species of the others are very numer- 

 ous and their mass is inconceivable. The Sargasso sea alone has 

 an area seven times as great as that of Germany and none of its 

 material can escape. Here is ample material ; contributions from 

 land plants are only accessory. The ash from sea weeds contains 

 no clay ; that from coal, lignite and peat consists of silicates not 

 belonging to plants and contains clay. This material is derived 

 from land detritus. The ammonia in distillates from coal is of 

 animal origin ; no accumulations in landlocked basins could have 

 animals enough to supply this ammonia, but Darwin and Meyen 

 have described the vast numbers of mollusks and other forms 

 attached to seaweeds. 



Sea plants are swept away, decay and sink or are distributed by 

 currents. They are heaped up to great thickness, there being 338 

 feet of coal in the Saarbruck basin. Darwin saw immense masses 

 of seaweed, floating, so constant in position that they are mapped 

 as reefs and sand banks. If a layer of leaf coal occur, it is evi- 

 dence only of material brought in from the land. The absence of 



^¥. Mohr, " Geschichte der Erde," Bonn, 1866, pp. 82-icx), 130, 137. 



39 



