SEDGWICK ON THE ROCKS OF N. WALES AND CUMBERLAND. 447 



seldom contorted, these beds must be of great thickness. They 

 produce workable slate, but no distinct fossil species have yet 

 been found in them. 



j3. A thin zone of calcareous slate with concretions of limestone. 

 This bed is only a few feet thick, and the rognons of limestone are 

 sometimes replaced by a singular cellular calcareous slate with 

 obscure casts of fossil shells. It ranges on the south of the Duddon, 

 and has been traced from point to point ; and after an interruption 

 of two or three miles it appears at Tottle Bank heights, from which 

 it may be traced over the neighbouring hills to a spot below Low 

 Hall farm on the east side of Coniston water. A third obscure 

 band of limestone is stated by the author to exist in the hills north 

 of Nibthwaite. 



The fossils of these bands of limestone are Upper Silurian ; 

 but though numerous they are very obscure.* In his letters on 

 the lake district, the author states that he has described these fossils 

 as Lower Silurian ; but the specimens alluded to were obtained 

 from High Haulme, three quarters of a mile S.E. from Ireleth 

 village. " The limestone there forms a ridge not exactly continuous 

 with the other limestone, which I accounted for by the interposition 

 of a fault. But there is no fault of the kind I supposed. The High 

 Ilaulme limestone is an independent ridge, the limestones and 

 the slates are vertical, and associated with great masses of felspar 

 rock and porphyry, exactly like the older slates below the Coniston 

 limestone, and when brought up against the newer series of slates, 

 these latter are thrown into most extravagant contortions."! 



y. The third subdivision of the great complex slaty group here 

 described is termed by the author the Upper Ireleth slates, and ex- 

 hibits remarkable examples of structure. These beds contain 

 round concretions, like those of the Coniston flags. They are of 

 great thickness, and alternate with beds of grit passing into coarse 

 sandstone, and, rarely, into a conglomerate. Following them from 

 Ireleth, where they are largely worked, to the Lev en sands, they 

 gradually pass into a coarser deposit without any regular line of 

 demarcation. These coarser beds also contain concretions, and, 

 though unfit for use, they continue to show a striped surface and 

 slaty structure. 



* The author adds in a note, " The enormous dislocation which throws for- 

 ward the Coniston limestone at the Water Head seems to affect the whole chain 

 of hills to the bottom of the lake. The corresponding beds on the opposite sides 

 of the lake are not in the prolongation of the lines of strike. The lake there- 

 fore occupies a line of fault, on the eastern side of which is an enormous upcast 

 of the whole series of rocks." 



■f The following is a list of the fossils collected at High Haulme from the 

 dislocated Coniston limestone : — 



Cyathophyllum Turbinolopsis bina 



Catenipora escharoides Spirifer crucialis 



Favosites fibrosa, and other species Orthis Actoniae 



Retepora, very large canalis 



Porites pyriformis inflata 



Astrea Calymene Blumenbachii. 



h h 2 



