_ 
Subdivisions of the Paleozoic Strata of Great Britain. 349 
suppose that this “lower formation” actually descends below the 
Old Red Sandstone of England, and is on the parallel of the 
tilestone and fish-beds of the " Silorian system ?” 
Il. Upper Paleozoic Division signi the Carboniferous 
and Permian rocks. 
k ae py ae ares coal fore of the basin of the Tweed, and lower coal- 
field o cotland. Under this group may, perhaps, be fina ally arranged the 
Datboctfene slates” of ire as and also the Marwood and Petherwin 
groups above mentioned. coal-field of the Tweed appears to include 
the “great sc dn lene of Derbyshire and Yorkshire, and even to de- 
scend below 
i Be shal” of Derbyshire, “ Yordale series” of Philli . 
s — “stone grit. A deposit ‘variable in structure and thickwes ss; seldom en- 
gach vag bee in Yorkshire, a complicated group of great thickness, and 
ds of co 
(4. Gr eat aioe coal-field of England, to be divided into two or three sub-groups. 
Upper Division continued. 
(1. Coarse red sandstone and conglomerate, hape ie! eater eer to the Car- 
boniferous strata. It con a (thou: amen rarely) true Carboniferous fossils 
(Lepidodendra, Stigmaric, &c.), which may, pakion: have been drifted me- 
chanically out ‘of the cheque coal-fields into this coarse, overlying, Per- 
Carboniferous Series, 
we * 
2. Marl-slate, and th thin-bedded compact limestone; a few i ee of plants 
shells o Palecaois genera—Productus, Spirifer ; some La edhivendiiics 
; many impressions of fishes—Palconiscus, latysomus, Papeplan Acro- 
epis, &e 
3. Mein limestone, in some parts of the north = or of great thick- 
, and most co complicate ted structure: ¢.g..rarely a crystalline dolomite, 
compact, cellular, earthy, ee , globular, oolitic, d&c., occ page ith 
organic remains— Produc us, Spirifer ; several Lanullibranchiate: Syno- 
C. 
Permian or Dolomitic Series. 
* ed’ By pseous marls, ve ry slightly saliferous, 
5. Thin-bedded gra ray role sometimes cellular and dolomitic. A few traces 
8, a 
si Syps marls, The above series is overlaid in the great red and var 
L riegated s ne which forms the base of the Tria 
stone of central England, would, I think, be perfectly erro- 
Neous. It would be the sacrifice of a natural and well-estab- 
