1846.] SEDGWICK ON THE SLATE ROCKS OF CUMBERLAND, ETC. 113 



Wales*. Fossils are extremely rare in this group ; but, after a care- 

 ful search, some have been discovered. Among these are Cardiola 

 interrupta, Graptolites ludensis^ and fragments of Trilobites. To 

 which may be added, Orthoceratites Ihex^ and O. suhundulatus of 

 Casterton Low Fell which belongs to this group. 



4. Ireleth Slates, Sfc. — These beds are thus subdivided : — 



^. Coarse slate and flags, &c. 



y. Upper or great Ireleth slates. 



(3. Upper limestone. 



a. Lower Ireleth slate. 



To enter on any elaborate description of this most complicated 

 group would involve me in almost endless details, and I must con- 

 tent myself with little more than an enumeration of leading points, 

 and refer to sections. 



4 a, or Lo2ver Slates, occupies a band of very highly inclined beds 

 more than half a mile broad, between the upper limestone of Tottle- 

 bank Fell and the zone of the Coniston grits. Under the line of 

 the same upper limestone (/3) there is at least an equal thickness of 

 slaty beds in the Ireleth country, on the south side of the Duddon 

 estuary. I refer the slates of Bannisdale Head and Bretherdale to 

 this sub-group. In general mineral structure it is almost identical 

 with the group (3) of higher slates, and there is indeed no definable 

 difference. I know of no fossils in this group in the Ireleth country 

 except Graptolites ludensis ; but, from the general absence of quar- 

 ries, they may exist and yet have escaped notice. 



4 /3, or Upper Limestone. — This limestone appears in five places 

 on the south-east side of the Duddon Sands. In this part of the 

 range it is of considerable thickness, and is still worked at Meer Beck 

 in a fine open quarry f. Most of the old quarries are deserted, as 

 good mountain limestone is found by the sea-side close at hand, for 

 economical use. Farther towards the north the band appears to 

 thin out; but it re-appears on the south face of Tottlebank Fell, in the 

 places indicated in my former paper. It is there very degenerate. 

 The limestone is shelly, but extremely impure. It is composed of 

 irregular discontinuous concretions, and it dies away on its line of 

 strike before it reaches Coniston Lake, and is not seen again, in any 

 appreciable form, farther towards the north-east. Fossiliferous 

 bands (with Terebratula navicida^ &c.) do however break out farther 

 to the north-east, nearly on the strike of this limestone, e.g. on the 

 right side of the road from Windermere Ferry to Hawkshead. 



* These halls, both in the grits and slaty bands, are of various sizes, — some- 

 times true septaria, sometimes filled with earthy ferruginous rotten-stone. They 

 follow the beds and not the cleavage planes, and among the more slaty masses 

 they are spheroidal, with their longer axes in the direction of the beds. On 

 the contrary, in the Millani quanics, the calcareous concretions of (he Coniston 

 limestone are formed on the cleavage planes, and not on the beds. 



t In one quarry there occur numerous specimens of a square-stemmed Enorinile 

 {Tctracrinites}'). 



VOL. II. — PART I. I 



