Ohsercations on the Occurrence of Anthracite. — Gresley. 17 
Prof. Thomas in " Coal Mine Gases and Ventilation,'' 1878, 
says, ''the anthracites are derived probably from organic ma- 
terials which become buried very rapidly under a considerable 
thickness of inorganic matter." In the coal basins of Mons, 
Valenciennes and Liege, the same coal beds which are decid- 
edly bituminous (gras) near the surface gradually become 
anthracitic as traced downwards till they pass into true 
anthracites. In viewing these French and Belgian regions 
we should bear in mind how the Coal Measures are squeezed, 
rolled up and faulted against or by very great thicknesses of 
older strata, evidently thrust up from once very much deeper 
and warmer regions. A fault exists somewhere in the Pas de 
Calais coal fields with a throw of about 1,200 feet, the down- 
cast side being towards the south. On each side of this frac- 
ture of displacement, at a depth of 900 feet or so, the percen- 
tages of volatiles in the coals was markedly different, those 
on the downthrow side having 28 to 30% as compared with 
only 12 to 18% in those on the upthrow side. This shows 
that the deeper the seams are the more anthracitic they get,, 
and that the loss of volatiles was brought about before faul- 
ting occurred. That somewhat similar phenomena are to be 
met with in the deeper shafts of collieries in North Stafford- 
shire, Cheshire, and Lancashire, the writer has reasons to be- 
lieve, at all events the deepest seams, as a whole, approach 
the characteristics of anthracite more than the uj)permost 
do. 
In the Prades coal-field, P"r;iiu'e, M. Koussellier described 
the Coal Measures as reposing in a basin of the Ardeche crys- 
talline rocks, those overlying and underlying the coal series 
being chiefly gneiss and mica-schist. The coals have variable 
dips, and locally, complete contortions are found. "The 
Coal Measures are chiefly composed of variable beds of sand- 
stone and conglomerate, there being very little shale." The 
measures are about 350 metres tliick. Tiio field is said to be 
ruptured by a modern volcano, but which "has in no way 
altered the Coal Measures." " Tlie coal is poor anthracite." 
Prof. E. Hull wrote of the Asturias coal region in Spain, 
the chief features of which are "coals belonging to three 
classes, viz., anthracite, setni-bitiiininous and bituminous." 
Tiie strata are thrown into high angles varjnng from 50*^ ta 
70'^ and the topography is decidedly liiliy. 
