STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 467 



into benches. The lowest seam, Hke Ste.-Barbe-de-Floriiffoux, has 

 the en chapelet structure and shows extraordinary changes in thick- 

 ness. The middle faisceau has i6 seams, 0.45 to i meter thick, 

 many of which have a faux-toit of gallet, or of shale and coal, and a 

 typical mur. The roof in some cases contains Naiadites and Car- 

 honicola. One seam has en chapelet structure ; intervals between 

 scams vary, apparently without rule. The Goufre or lowest fais- 

 ceau is the most important, having 10 workable seams, 4 of them 

 more than i meter thick, and all more regular than those of des 

 Ardennoises. The highest seam, V. Anthracite, is often absent, 

 having been removed during deposition of the overlying sandstone, 

 which occasionally reaches almost to the V. Caillette, 3 meters below. 

 V. Anthracite is seldom thicker than 30 centimeters and its coal has 

 but 8.80 per cent, of volatile, much less than that in any seam below 

 it. The V. Tatonie has sandstone pebbles and is very close to the 

 underlying Gres de Hamm, which is 10 to 12 meters thick and closely 

 resembles the poudingue houiller; like that, it contains grains and 

 pebbles of bright coal. The thickest seam, Dix-Paumes, has 1.28 

 meter of coal on the north and south sides of the basin, but is much 

 thinner midway. It contains pebbles of quartzite and fragments of 

 gallet, a cannel-like shale. The coal is excellent, with 16. i per cent, 

 of volatile and only 3.5 of ash. V. Gros-Pierre, Stenaye of the Liege 

 district, is irregular, usually present at the east but disappearing 

 toward the west. It has, at most, 0.93 of coal in 4 benches ; its coal 

 has a fibrous structure and frequently contains pebbles of quartzite. 

 Its thin faux mur rests on sandstone, which has Stigmaria in the 

 upper part. A cross-bedded sandstone is persistent in the faisceau 

 Goufre. The conditions farther west in Hainaut are not materially 

 different from those already described. 



The Flenu deposits are confined practically to the district of 

 Couchant de Mons, in much of which the coal is buried deeply, but 

 mining operations are extensive. The coal is much richer in volatile 

 than that of the Charleroi but peculiarities of seams and of the inter- 

 val rocks are much the same. The lowest seam^^ is the Petit- 

 Buisson, which has a well-marked marine roof, whence Cornet ob- 



^3 J. Cornet, "Seconde note sur les lits a fossiles marins," etc., Ann. 

 Soc. Geol. Belg., t. XXXIV., 1907, Bull.., p. 93. 



