I 



Vol. 57.] PENDLESIDE GEOUP AT PENDLE HILL, ETC. 393 



stones of the whole of the Lower Carboniferous rocks of the North 

 of England, which therefore were the result of denudation by a 

 different river-system from that of the Upper Carboniferous Series. 

 If this be so, it is easy to understand why the Pendleside Group is 

 limited to the north and does not occur between the Grits and the 

 Toredale Series, and to perceive the great factor which limited the 

 distribution of the Pendleside Limestone Group to so definite and so 

 comparatively small an area in Central England and Ireland. 



The extent and comparative thicknesses of the Pendleside Group 

 are shown in PI. XIY ; these were arrived at by estimating the 

 thickness of the deposit wherever strictly reliable evidence could be 

 obtained. 



On the eastern side of the Derbj'shire and Staffordshire anti- 

 cline at Matlock the group is almost 400 feet thick ; still farther 

 north, in the neighbourhood of Eyam, the thickness is 300 to 350 feet, 

 and presumably it is almost the same around Castleton, the thickness 

 being calculated from the Pendle, Earey's, or the Yoredale Grit to 

 the top of the massive limestone. Coming rouod to the western 

 side of the anticline in the railway- and tramway-cutting north of 

 Doveholes Station the beds are about 400 feet thick, but on the 

 Cheshire side, where the Lower Millstone Grits are not so well 

 developed, the whole series between the Third Grit and the limestone- 

 massif is about 1000 to 1200 feet ; deducting 500 to 600 feet as the 

 representatives of the Kinderscout and Earey's Grit, it will be seen 

 that the Pendleside Group is not very much thicker here than on 

 the eastern side. This increase of thickness is explicable, and seems 

 due to the fact that about 500 feet below the Third Grit on 

 Congleton Edge a series of thick quartzose, gannister-like sand- 

 stones occur, which probably represent the Earey's Grit. 



The Pendleside Group at Pendle may be estimated at 2300 feet, 

 showing a great increase in thickness as compared with that which 

 obtains in Derbyshire. Unfortunately, between Castleton and 

 Clitheroe the limestone - massif is not exposed, consequently no 

 base-line is available for calculating the thickness of the Group in 

 the Calder Yalley. 



North of Pendle the beds rapidly thin out till at Thorpe, near 

 Burnsall, the Group is only 450 feet thick. 



Assuming an east-north-easterly or north-easterly direction for 

 the source of the material, the axis of greatest thickness would 

 lie obliquely from Pendle to Congleton, gradually thinning as it 

 passed southward ; but south and south-east, and north and north- 

 west, of this axis, that is, towards the edges of the basin, the 

 deposits would become much thinner, and they are so in fact. 



V. Chemical Chaeactees of the Pendleside Limestones. 



Although it cannot be said that a few analyses of limestones 

 gathered from isolated points over a wide area are of any value for 

 stratigraphical purposes, yet the following chemical analyses, kindly 



