Parr II. Sxcr. iv. § 2.] CARBONIFEROUS. 745 
-many detached areas or basins—the result partly of original deposition, 
partly of denudation, and partly of the spread and overlap of more 
recent formations. There can be no doubt that the English Car- 
boniferous Limestone once extended continuously eastward across the 
north of France, along the base of the Ardennes, through Belgium, and 
across the present valley of the Rhine into Westphalia. From the 
western headlands of Ireland this calcareous formation can thus be 
traced eastward for a distance of 750 English miles into the heart of 
Kurope. It then begins to pass into a series of shales and sandstones, 
which, as already remarked, represent proximity to shore like the 
similar strata in the north of England and Scotland. In Silesia, and 
still much further eastwards in central and southern Russia, repre- 
sentatives of the Carboniferous Limestone appear, but interstratified, as 
in Scotland, with coal-bearing strata. Traces of the same blending of 
marine and terrestrial conditions are found also in the north of Spain. 
But over central France, and eastwards through Bohemia and Moravia 
into the region of the Carpathians, the Coal-measures rest directly upon 
older Paleozoic groups, most commonly upon gneiss and other crystalline 
rocks. These tracts had no doubt remained above water during the 
time of the Carboniferous Limestone, but were gradually depressed 
during that of the Coal-measures. 
France and Belgium.—In Belgium and the north of France 
the British type of the Carboniferous system is well developed.! It 
comprises the following subdivisions: 
(Zone of the gas-coals (Charbons a gaz, rich bituminous coals, with 28 to 40 
‘per cent. of volatile matter), containing 47 seams of coal. Pecopteris 
nervosa, P. dentata, P. abbreviata, Alethopteris Serlii, Neuropteris hetero- 
phylla, Sphenopteris irregularis, S. macilenta, S. coralloides, S. herbacea, 
S. furcata, Calamites Suckowii, Annularia radiata, Sphenophyllum 
erosum, Sigillaria tessellata, S. mamillaris, S. rimosa, 8. laticosta, 
Dorycordaites. 
Zone of the “ Charbons gras” (18 to 28 per cent. volatile matter), soft 
eaking coals (21 seams), well suited for making coke. Sphenopteris 
nummularia, S. macilenta, S. cherophylloides, S. artemisifolia, S. herbacea, 
S. irregularis, Neuropteris gigantea, Alethopteris Serlii, A. valida, 
Calamites Suckowii, Sphenophyllum, emarginatum, Sigillaria polyploca, 
S. rimosa, S. laticosta, Trigonocarpon Negerathii. 
Zone of the “ Charbons demi-gras” (12 to 18 per cent. volatile matter), 29 
seams of coal, chiefly fitted for smithy and iron-work purposes. Spheno- 
pieris convexifolia, S. Hoeninghausi, 8. trichomanoides, S. furcata, S. 
Schillingsti, S. irregularis, Lonchopteris rugosa, Calamites Suckowii, 
Annularia radiaia, -Sigillaria mammilaris, S. elegans, S. piriformis, 
S. elliptica, S. scutellata, S. Groesert, 8. levigata, S. rugosa, Halonia 
tortuosa. 
Zone of the “Charbons Maigres.” Lean or poor coals (20 to 25 seams), 
only fit for making bricks or burning lime (9 to 12 per cent. volatile 
matter). Pecopteris Loshii, P. pennexformis, Neuropteris heterophylla, 
Alethopteris lonchitica, Sphenophyllum saxifragzfolium, Annularia radiata, 
Sigillaria conferta, S. Candolli, 8. Voltzti, Calamites Suckowti, Lepido- 
dendron rhodeanum, L. pustulatum, Lepidophloios laricinus. 
Zone of Productus carbonarius. Goniatites diadema, G. atratus, Spirifera 
mesogonia, S. glabra, S. trigonalis, Orthis crenistria, Productus semi- 
\_ reticulatus, P. marginalis, Avicula papyracea, Schizodus sulcatus. 
Sandstone or quartzites passing into conglomerates, separated from the 
:} Carboniferous limestone below by carbonaceous shales with some thin 
coal-seams; chiefly developed towards the north-east (Liége, Aix-la- 
Chapelle. ) 
' Gosselet’s Esquisse, Mourlon’s “ Géologie.” 
Coal-measures—Systeme (Htage) Houiller. 
Millstone 
Grit 

