DEPOSITED IN WATER. 
35 
character corresponding with the well-known sections of Derbyshire ; 
but in tracing it northwards we find the type changed, and the 
simple calcareous series varied with interpolations of other rocks. On 
the northern border of the lake district, its divided lower members 
alternate with red sandstones and clays, — in all the escarpments north 
of Brough its upper beds form the predominant parts of a com- 
pound group, with sandstones, shales, (plates), and coal ; and as we 
proceed through Northumberland these new terms of the series aug- 
ment in thickness, predominate over the diminished and deteriorated 
limestones, and change the aspect of the region, from the green ver- 
dure and dry rock of limestone, into the brown heath and wet 
surfaces of a poor tract of coal measures. The same variations of 
type, operating in the same directions, are traceable in the interior 
of the district, as far as the upper parts of the rock are concerned. 
In Nidderdale the great mass of limestone is covered by black shales, 
thin black limestones, and cherts, of the Craven series. In the upper 
ends of Ribblesdale and Dentdale, and generally around Wharnside, 
the broad upper layers of the limestone alternate with shales. In 
Yoredale these shales thicken so as to be recognizable beds, (Ask- 
rigg, Aysgarth,) and to separate the calcareous layers called the Gale 
limestone in Wensleydale, and the Tyne bottom limestone in Aldstone 
moor. 
In this progressive change of character to the northward, we lose 
by degrees the distinction of lower scar limestone, and it becomes 
not only difficult to draw the line for its upper boundary, but doubtful 
whether it is proper to make such an attempt. In the northern 
parts of Northumberland it appears neither desirable nor possible to 
separate the lower from the similar middle and upper calcareo-car 
boniferous groups ; and in the same country the alternations of the 
lower beds, with red sandstones, serve to prove how very imperfect 
would be our views of the contemporaneous physical piocesses in 
different parts of the ancient sea, if founded on merely local (how- 
ever well observed) phenomena. In all the vast thickness of strata, 
which for distinction we break into systems and consider in sections, 
F 2 
