Yol. 57.] PENDLESIDE GROUP AT PENDLB HILL, ETC. 391 



-of Carboniferous rocks, and accounts for the apparently sudden 

 character of the change. 



As previously remarked, in the Barrow and Grange district the 

 great mass of limestone is undivided ; and on the east, along the 

 line of the Nidd, and the eastern part of Wharf edale, the limestone 

 is undivided for a considerable distance farther north than is the 

 case between these limits. The influence of the high land of th& 

 Lake District in limiting the deposition of grits and shales in the 

 Carboniferous area south and west is very apparent. Similarly the 

 influence of the great east-and-west barrier of high land extending 

 across Central Wales to Charnwood, and possibly even from the- 

 Wicklow Hills, prevented the deposition of the whole of the Lower 

 Carboniferous rocks for some distance south of the Pennine basin. 



Even as far south as Derbyshire a short series of passage-beds, 

 shales and limestones, are found at the top of the limestone, showing: 

 that this area had then come within the limits of mud-laden water. 

 Thus the Carboniferous Limestone Series of Scotland and the N'orth 

 of England, the Great Scar Limestone and the Toredales, and the 

 Carboniferous Limestone of Central England, that is to say, the 

 whole Pennine system, tell all one story, and form a fairly complete 

 epitome of the various synchronous deposits which may be laid 

 down in waters close enough to land to be aff'ected by rivers and 

 currents, a view supported largely by palaeontological evidence- 

 of the migration of species and genera, as shown in the tabular 

 diagrams (figs. 2 & 3, pp. 380 & 382). 



The Millstone Grit area of Great Britain is much more limited 

 than might be supposed. The whole series forms a lenticular mass, 

 with a maximum deposit in the district between Pendle Hill and 

 Kinderscout. 



As the series passes northward, southward, and westward, both the 

 thickness and number of the beds diminish rapidly, but on the east the 

 grits disappear beneath newer measures, and nothing can be stated 

 about them. We know that the Grit Series is absent in the Isle of 

 Man, the Barrow district, Leicestershire, Shropshire, and South 

 Staffordshire, and is of little moment in North Wales, if it be 

 really present there. It has always appeared to us that the beds i» 

 Scotland referred to the Millstone Grit are neither more nor less than 

 Coal-Measure sandstones. In several places beds of coal are found 

 between the Grits, especially in the area of their maximum deposition ; 

 and, although in the Midlands the Millstone Grit Series forms a 

 well-marked subdivision, even in that area there is much uncertainty 

 as to the base, for it is preceded by a series of thin sandstones. More- 

 over, thick quartzose sandstones occur in the Lower Coal-Measures,. 

 very difiicult at times to distinguish from the beds mapped as Grits. 



The area of maximum deposition of the Grits corresponds also to 

 the area of maximum deposition of the Pendleside Limestone Group, 

 which is even more limited in area than the Grit Series. The Grits 

 overlap the Pendleside Group considerably to the north. 



