30, 31, with the Hawes section p. 38, will prove in addition that the development of these grits, and shales, and coal, is proportioned to that of the Cam limestone, so that the deposition of both groups may be referred to the same agencies. The geographical origin of these agencies may be satisfactorily inferred from the local amount of their effects; the nature of the agencies is indicated by the mineral nature of the deposits; and from the whole combined we may believe that the line through Jervaux abbey, Kettlewell, Ryeloaf, and Lancaster, divides the oceanic from the littoral portion of the great mountain limestone deposits.

Parting from below Great Whernside, as a centre, we find that along the whole length of Coverdale, stretching fifteen miles to the north-east, parallel to the coast line, the thickness of plates and grits above the middle lime, augments from eighty to only one hundred and fifty feet;-in an easterly direction it is diminished to thirty, and in a southerly and south-easterly direction appears to vanish altogether. In like manner all the flagstones and plates under the middle limestone, in Great Whernside, are included in a space of one hundred and fifty feet: this space augments on the north by east to four hundred and eighty feet, on the north-west (Hawes) or proceeding directly toward the ancient shore, to seven hundred and eighty feet, on the west (Penyghent) to three hundred feet; but on the east, south-east, and south proceeding toward the deep sea, it is reduced to nothing.

The influence of land inundations, and littoral movements is greatest toward the north-west, where the slate ranges of Cumbria had been uplifted; the purely oceanic character of the limestones is greatest toward the south-east, where land was in that æra very distant.

South-Western Districts of the Yoredale Series.-Proceeding to the S. W. for the purpose of connecting the general base of the series, in Wensleydale, with that in Ribblesdale, and passing over the intermediate mountains by Weather fell, (or Bear fell), Dod fell, and Cam fell, we obtain the following results. The surface of the lower limestones rises from Wensleydale to Ribble head, nearly two hundred feet; the Yoredale series is about one thousand feet thick; in

passing from Weather fell to the eastern end of Cam fell, the interval between the main and underset limestones, (only forty feet in Weather fell), continually diminishes; the underset limestone, which is fifty feet thick over Wensleydale, becomes much thinner, and finally the two rocks appear united in one crinoidal limestone in the southern front of Cam fell, over a great mass of flagstones and plates; detached masses of the millstone grit series lie over this limestone in Weather fell and Dod fell). Crossing the rather obscure country of plates, grits, and limestones, between Cam fell and Ribble head, we find the same series in Ingleborough, composed in like manner, of about five hundred feet of plates and laminated grits, with limestones and plates at the bottom; on this rests crinoidal limestone rock, thirty feet thick, covered by alternating grits and plates; and the whole is crowned by a pebbly millstone grit. This, which we shall in future designate as the Ingleborough grit, is the same as that already noticed above Kettlewell and in Nidderdale. In Penyghent also the main limestone occurs under a cover of Ingleborough grit, inclosed in shales, and flagstones with COAL, There is no underset limestone.

The whole series, above five hundred feet thick, was thus observed, (1833).

20 Limestone (Simonside), in great beds, blue below, gray above,

small crinoidal.

62

40

Feet.

20 Gritstone (and plate).

3 Limestone (sandy, hard blue).

3 Plate.

6 Hard micaceous grit.

30 Plate.

Hardrow scar. limestone, with lithodendra, and turbinolia, and

South of Penyghent, we have the Hardrow beds well exhibited.

a. Chert caryophyllia in black limestone, loose corals in the soil,

the limestone having decomposed.

b. Black limestone with productæ.

c. Shale.

d. Dark rough limestone.

e. Ditto.

f. Gray limestone. In the shales are spiriferæ, crinoidea, ortho

ceras.

In Fountains fell, the upper limestone resembles that in Penyghent, but is not so thick, there is no underset limestone. It is covered by the Ingleborough grit, alternating with shales and COAL.

45. Limestone, dark and gray with chert in beds and nodules, few fossils

100.

{

Thick shale, near the middle are two layers of sandstone. In the shales below, abundance of ironstones, in one of which ammonites were found.

Near the bottom a thin layer of cherty rottenstone.

Northern districts of the Yoredale Series.-We may now proceed to trace the character of the Yoredale series in the country farther north. Swaledale, which runs from west to east parallel to Wensleydale, Arkendale which runs in a south-east direction and enters the left bank of the Swale, the vale of the Greta, Lunedale, and Teesdale, with the escarpments of the Penine chain, will afford us sufficient data for this research. It must, however, be observed, that not one of the valleys named, nor any other lying to the north of Wensleydale, shews so completely as that the lower scar limestones which are the general base of the system.

Swaledale. This great valley is remarkable for commencing at a very high mountain pass, in beds above the whole of the Yoredale limestones; it then excavates its passage through the main, underset, middle, Simonside, and Hardrow limestones, and again crosses these rocks as they necessarily sink eastward faster than the stream. The lower limestones are best seen about Muker, the upper belt is every where conspicuous. In a general sense, and as compared with Yoredale, Swaledale may be said to be in a depression of the strata. It is full of dislocations. Five lines of section have been attended to in connecting the Yoredale and Swaledale series: the first is from Hawes to Muker, over Stag fell, and down Cliff gill; the second from Askrigg to Muker;

H

the third from Redmire by Bolton castle to Reeth; the fourth from Leyburn to Reeth; the fifth from Leyburn to Richmond.

On ascending from Hawes to Stag fell and Lovely seat, we have the Yoredale section well exhibited, except for a part between the Simonside and underset limestones; the middle limestone is not clearly seen in this thick flagstone series.

(50
50

Gritstone.

Flagstone.

Plate.

Limestone called underset in Swaledale (here thicker than usual, having chert on the top of it).