I9I3.] STEVENSON— FORMATION OF COAL BEDS. 135 



sidering the extent of area whence driftwood has been drawn, the 

 quantity stranded on coasts is remarkably small. It has been 

 gathered by great rivers of America and Asia to be distributed by 

 currents, which have originated since the Carboniferous. 



Conditions on the Amazon, Congo and other tropical rivers lend 

 no countenance to the assertion that great sheets of floating vegeta- 

 tion might have been brought down by rivers into estuaries to aid 

 in formation of coal beds. Those great streams, in time of flood, 

 unquestionably carry matted vegetation in considerable quantity. 

 Earlier pages of this work contain descriptions by travellers, which 

 show little tendency to scientific accuracy, but suffice to prove that 

 the material, thus transported, is far from insignificant. At the 

 same time, granting that strangeness of the phenomenon did not lead 

 the traveller to exaggeration and granting that the statements do not 

 tell even half of the truth, the relevance of the occurrences may well 

 be questioned. No reason has ever been presented to justify a sug- 

 gestion that streams, such as have been named, could have existed 

 as tributaries to estuaries, in which one now finds the Westphalia- 

 Nord coal basins ; nor is there any ground for supposing that if they 

 had existed, they would have carried the imagined sheets of plant 

 materials. 



It is difficult to understand why the observations by A. Agassiz 

 have been regarded as supporting allochthony, since they in no wise 

 bear on the questions at issue. There was nothing novel about them 

 except the localities. Every one knew that the muds of ponds and 

 lakes contain twigs, leaves, pollen and spores as well as occasional 

 larger fragments of wood. It was equally well known that the silts 

 on river banks contain transported fragments of plants ; that the 

 Mississippi and the Orinoco deliver vast quantities of driftwood 

 into the Gulf of Mexico and the Caribbean sea, and the devastating 

 effects of West Indies hurricanes have been described by many 

 writers. If the trawls had not brought up much plant material with 

 the muds of the Caribbean and those off the California coast, the 

 condition would have been inexplicable. But Agassiz found no evi- 

 dence of a coal bed in process of formation, he found no evidence of 

 sorting of materials through influence of gravity, he found no proof 



