i9>'-7 STEVEXSOX— FORAIATIOX OF COAL BEDS. 643 



to be evidence that it was transported, because one cannot believe 

 that it would resist decay long enough to permit accumulation about 

 it ; yet the condition is familiar, for even the slender canes of the 

 ^Mississippi delta, killed by salt water invasion, remain standing after 

 they have been surrounded by several feet of silt. The filling of 

 stumps by sand or clay is regarded as evidence that the change 

 occurred after complete entombment in the mass of transported 

 material ; yet Potonie has shown that stumps on the shores have been 

 found with the decayed interior replaced with sand even into the 

 roots. 



Some authors have laid no little emphasis on the Alartigny 

 debacle as showing that landslides may explain those buried forests, 

 whose ill situ appearance cannot be denied. But aside from the fact 

 that landslides are wholly exceptional and for the most part of lim- 

 ited extent, one may not utilize them as an explanation, unless it be 

 supposed that, during the Carboniferous, landslides could occur amid 

 conditions which would make them impossible now. According to 

 some authors, the great coal areas were level regions ; according to 

 others, they were water basins, surrounded by a vast expanse of 

 level area, forested or swampy. Under such circumstances a land- 

 slide like that of Alartigny or even like that on the lower Adige 

 could affect only the far away border area. But, in anv event, the 

 evidence of a landslide would be unmistakable ; there would be no 

 room for conjecture. The rock of the slide would be dift'erent from 

 that at the same horizon a little distance away ; and there would be 

 ample evidence of disturbance in the underlying rocks, produced by 

 downrush upon the water-soaked materials : certainly evidence of 

 the debacle would not be wanting. But no such evidence has been 

 reported from any locality ; on the contrary, where detailed descrip- 

 tions have been given, one finds that the bedding is undisturbed and 

 the conformability is complete. Equally, the buried trees are not 

 relics of floating islands such as those of the Amazon and Congo, for 

 they are not associated with filled valleys, but stand in and on rock 

 of the type prevailing at the horizon for long distances. 



241 



