140 STEVENSON— FORMATION OF COAL BEDS. [April i8, 



debris are gathered up to be mingled with inorganic debris from the 

 channel-way. 



But there are floods, caused by cloud-bursts at the heads of 

 streams with rapid fall in narrow gorges, which are destructive 

 throughout. Such floods, loaded with coarse and fine rock material, 

 scour the little flood-plains, removing soil and trees alike, the latter 

 to be deposited with the mass of mineral debris in any or all posi- 

 tions, vertical, prostrate, inclined or reversed ; and with them would 

 be rootless stems broken off from the caiion walls. The condition is 

 wholly similar to that caused by the bursting of a dam, as in the 

 Johnstown or the Lake Bagne disaster. A torrent flowing in a 

 gorge of gneiss or granite, especially if it be so juvenile as those 

 imagined by Fayol and de Lapparent, would be a succession of falls 

 and rapids, over which trees could not be carried unless the depth of 

 water was such as comes from a cloudburst. It is deserving of note 

 in this connection that plant remains occur very rarely in the Siwalik 

 conglomerates, which, as described by Medlicott, were brought down 

 by the fierce torrents of the Himmalayan slope. The small quantity 

 of vegetable materials in Coal Measures sandstones is a remarkable 

 phenomenon, for sandstones certainly tell of greatly increased activ- 

 ity in the streams. 



But it is evident from the statements by Fayol and de Lapparent 

 as well as by several others who have been cited, that the supply of 

 plant material comes not from immediate vicinity of the gorges but 

 from the whole drainage area. The difficulties in the way of this 

 suggestion are very serious. The upland region of Fayol and de 

 Lapparent must have been covered with a forest, denser than any in 

 the temperates and with an undergrowth like that of a tropical 

 jungle. Renault goes farther and thinks the vegetation of those 

 days more exuberant than that of the tropics at this time. This 

 condition makes the asserted results impossible, so that the concep- 

 tion hardly deserves the exultant compliment by de Lapparent, that 

 it is a triumph of common sense. 



If the flood gates of heaven were opened and the flow of water 

 concentrated on one spot so as to work underneath the vegetable 

 cover, the whole surface would be stripped of soil and all else ; but 



