INTRODUCTION. XXV 
its upper beds appears to sanction the conclusion. If this conclusion be received, it will 
follow that the Devonian series of Herefordshire is defective at its upper extremity, while 
the same series in Devon and Cornwall is defective at its base. 
But if we take the Devonian series of Scotland as our type, a still more remarkable 
conclusion seems to follow: viz. that the Devonian series of Herefordshire (spite of its 
apparent passage into the Tilestone) is also defective at its base. For we have little or 
nothing in Herefordshire to match the first three great groups, or “lower formation,” of 
Miller. May we not, however, 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 “Silurian System” ? 
Ill. Upper Palewozoie Division including the Carboniferous and Permian rocks. 
{1. Great scar-limestone: coal-field of the basin of the Tweed, and lower coal-field of Scotland. Under 
this group may, perhaps, be finally arranged the ‘“ Carboniferous slates” of Ireland, and also the 
Marwood and Petherwin groups above mentioned. The coal-field of the Tweed appears to include 
| the ‘great scar-limestone” of Derbyshire and Yorkshire, and even to descend below it. 
2. ‘* Limestone shale” of Derbyshire, ‘ Yordale series” of Phillips. 
; 3, Mill-stone grit. A deposit variable in structure and thickness; seldom entirely wanting; in York- 
shire, a complicated group of great thickness, and containing beds of coal. 
4, Great upper coal-field of England, to be divided into two or three sub-groups. 
Carboniferous Series. 
Upper Division continued. 
1. Coarse red sandstone and conglomerate, generally unconformable to the Carboniferous strata. It 
contains (though rarely) true Carboniferous fossils (Lepidodendra, Stigmarie, &c.), which may, 
| perhaps, have been drifted mechanically out of the contiguous coal-fields into this coarse, overlying 
Permian sandstone. 
2. Marl-slate, and thin bedded compact limestone; a few impressions of Plants; shells of Palzeozoic 
genera—Producta, Spirifer ; some Lamellibranchiata ; many impressions of Fishes—Palconiscus, 
Platysomus, Pygopterus, Acrolepis, &c. 
3. Magnesian limestone, in some parts of the north of England of great thickness, and most complicated 
structure: e.g. rarely a crystalline dolomite, compact, cellular, earthy, brecciated, globular, oolitic, 
&e., occasionally with organic remains—Producta, Spirifer ; several Lamellibranchiata ; Synocladia 
Fenestella, &c. 
Red gypseous marls, very slightly saliferous. 
Thin-bedded gray limestone, sometimes cellular and dolomitic. A few traces of bivalves, &e. 
Red gypseous marls. The above series is overlaid by the great red and variegated sandstone which 
forms the base of the Trias. 
Permian, or Dolomitic, Series. 
CORE a 
— 
The preceding six groups are derived from the sections of Yorkshire and Durham, where 
the series is best developed. It is evident from the description of these groups, as well 
as from their general want of conformity to the Carboniferous groups, that the Permian 
series of England is physically more nearly connected with the Triassic than with the 
Palxozoic rocks. But its fossils (even without including the undoubted Carboniferous 
d 
