STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 465 



it decreases toward the east, becoming only 150 beyond Namur. 

 Three coal seams are in the middle stage (Andenne), all of which 

 are mined locally in the eastern part of the basin. Calamites and 

 Stigmaria are abundant. A thin coal seam near the top has a marine 

 roof. Conglomerate is of only sporadic occurrence in the Pou- 

 dingue houiller. 



Stainier,^^ in the Charleroi and Basse Sambre districts, found the 

 equivalent of the Andenne Plateur-de-Rouvroy in the Veine du 

 Calvaire, which is 50 to 60 centimeters thick ; it has been mined for 

 many years. This bed is at no meters below the Poudingue. The 

 lowest seam, Fort d'Orange, is half a meter thick and yields an ex- 

 cellent coal of the terroulle type, its composition being: volatile, 10.5 ; 

 fixed carbon, 84.34; ash, 5.16. The coal seams are all very thin in 

 Charleroi and a similar condition exists in Couchant de Mons. 

 Cornet^^ has shown that the Chokier fauna in the latter district is 

 wholly marine, but of littoral type. The deposits are fine-grained, 

 but he shows that this is no proof of deep water, for the great pro- 

 portion of the forms are mollusks with byssus. Seventy per cent, 

 of the Coal Measures deposits are fine material. He is convinced 

 that lowland surrounded the area of deposition. 



The Westphalian (Upper Westphalian) has, in ascending order, 

 the assises of Chatelet, Charleroi and Flenu. 



The Chatelet is poor in coal and the seams are thin, though less 

 irregular than those of the Andenne. In the Liege district, two 

 seams are worked, Chesson and Grande Pucelle or Desiree, 70 and 

 60 centimeters thick.^° The former has a marine roof, which Dan- 

 nenberg believes equivalent to that of Ste.-Barbe-de-Florif¥oux in 

 Charleroi district and very probably to that of Breitgang in Esch- 

 v/eiler, Finefrau-Nebenbank in Ruhr. The coal of Grande Pucelle 

 has 16 per cent, of volatile at the south, but only 6 per cent, in the 

 northern, the less disturbed portion of the district. Very little of 

 the Chatelet remains in the Andenne district and but one seam is 

 m.ined. This, the Chenevis, at 120 to 160 feet above the poudingue 



58 X. Stainier, " Stratigraphic, etc., de Charleroi et de la Basse-Sambre," 

 Bull. Soc. Belg. de Geol., t. XV., 1901, Mem., pp. 1-60. 



^9 J. Cornet, " Le terrain houiller sans houille (Hi a)," Ann. Soc. Geol. 

 dc Belg., t. 33, 1906, Mem., pp. 139-152. 



^^ A. Dannenberg, op. cit., p. 280. 



