474 STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 



The pebbles differ in character. Some are of feldspathic sand- 

 stone, the feldspar being completely decomposed. These, at times, 

 contain fragments of Coal Measures plants. Others are quartzites 

 of types belonging to the Coal Measures ; but there are some which 

 appear to be of Cambro-Silurian origin, though without fossils and 

 some are of gneiss. Eighty-six per cent, are from the Coal Meas- 

 ures, 2 from Cambro-Silurian and 12 are from the Archean. The 

 Carboniferous specimens are from the Flines (Andenne) and Cho- 

 kier assises (Namurien of Stainier). The forms vary; subangular, 

 63 per cent., and rolled, 37. The weights are i gramme to i kilo- 

 gramme, 73 per cent. ; i to 10 kilogrammes, 24 per cent. ; and still 

 heavier, 3 per cent. The largest are of sandstone. 



There must have been land where coal rocks and those of earlier 

 age were exposed. The area of outcropping coal rocks must have 

 been extensive and near at hand, as is evident from shape of the 

 specimens. These were from the north side of the trough, where 

 the rocks had become hard before tectonic disturbance occurred. 

 All efforts to explain their presence as due to torrential action must 

 be abandoned. The pebbles had been exposed for a long time; 

 some were wasted by rubbing, others seem to have been worn by 

 moving strata or by wind action ; but all evidence shows that they 

 endured long alteration in free air. 



Erect Stems — Stainier^* has described erect trunks observed by 

 him at two localities. At the Falisole colliery, the Veine Lambiotte 

 rests on a sandstone, containing a veinette, which occasionally unites 

 with the main seam. At usually 4 but occasionally 12 meters above 

 the coal is a veinette, which at one locality unites with it. In this 

 interval numerous trunks were seen, but they are without roots and 

 all features indicate that they are merely " snags." At the other 

 locality, the trunks are cut off by faulting, but the evidence presented 

 by Stainier does not suggest that the stems are in loco natali. The 

 seam at this place shows signs of erosion during deposition of the 

 overlying sandstone. Smeysters^^ has described the mode of occur- 



"^ X. Stainier, " Un gisement de troncs d' arbres debout au Charbonnage 

 de Falisole," Bull. Soc. Belg. de Geol, t. XVII., 1902, Mem., pp. 69-76. The 

 same, 1903, pp. 539-544- 



'''* J. Smeysters, "Note sur les troncs d'arbres fossiles," Anyi. Mines de 

 Belgiquc, t. X., 1905, pp. 1-12. 



