39 



1828. Jan. 4. — John Murray, Esq. Jun. of Albemarle Street, Lon- 

 don ; Henry Tuffnell, Esq. of Christchurch, Oxford ; The Right Hon. 

 Viscount Cole, of Christchurch, Oxford • R. C. Fergusson, Esq. M.P., 

 of Craigdarroch, Dumfriesshire, and of Great Cumberland Street, 

 London ; John Phillips, Esq. of York ; and John Gurdon, Esq. of As- 

 sington Hall, Suffolk, — were elected Fellows of the Society. 



The reading of Mr. Phillips's paper, begun at the last meeting, was 

 concluded. 



The object of this paper is to describe the geological structure and 

 relations of a group of rocks, which the author characterizes as " aber- 

 rant from the slate district of Cumberland," and extending about 

 fifteen miles towards the east under the summits of Greygarth, Ingle- 

 borough, and Pen-y-gant ; — a tract remarkable for the variety and sin- 

 gularity of its geological appearances, among which the proofs of 

 dislocation are peculiarly striking and important. 



To this description a sketch is premised of the slate -series of the 

 Lakes of Westmoreland and Cumberland ; where the rocks are grouped 

 in three principal divisions, the lowest consisting of dark soft slate 

 much contorted, with fine-grained gneiss beneath it passing into 

 granite. The second division occupies a country of very different 

 aspect from that of the slate : the mountain-ranges being marked by 

 abrupt precipices, as at Helvellyn, Langdale-Pikes, and the Lakes of 

 Ulswater, &c. and consisting of brecciated argillaceous rocks contain- 

 ing calcareous spar, green-earth, and calcedony, with greenstone and 

 other forms of trap. On the south of this chain is a tract of transi- 

 tion limestone, containing caryophylliae, products, spiriferee, and other 

 fossils ; and this is covered by a third zone of slate, the most recent 

 rock of the country, usually divisible into rhomboidal blocks, of which 

 two principal varieties are observable, alternating with each other ; the 

 one homogeneous and fissile, and containing organic remains spa- 

 ringly distributed, of the genera trigonia, pecten, gryphea, turritella 

 and terebratula ; — the other more granular and micaceous. This for- 

 mation is in some cases succeeded by red conglomerate, but more 

 commonly by mountain-limestone, the lowest beds of which contain 

 numerous pebbles of slate and quartz ; and above the limestone are 

 the carboniferous rocks, including the millstone grit and the upper 

 coal-measures. The highest strata known in the country, consist of 

 the new red sandstone, placed in an unconformable position above 

 the coal formation. 



The tract, which is the more immediate object of this paper, extends 

 from the valley of the Lune in an easterly direction, to that of the 

 Wharfe. Along its middle, from Casterton Fells to a few miles east 

 of the Ribble, ranges an almost continuous line of argillaceous rocks, 

 generally fissile, and belonging to the third division of slates above 

 mentioned. This tract is bounded on the north by the elevated strata 

 that support the summits of Greygarth and Pen~y-gant ; and on the 

 south (in consequence of great dislocations) by millstone grit and the 

 coal measures. If the rivers Lune and Wharfe are included, no fewer 

 than nine streams cross the district from north to south, and exhibit 



