I/O CARBONIFEROUS. 



ridges of Harrop Edge, Millstone Edge, Diggle Edge, Charnel Rocks, \YarIo\v 

 Pike, Hanidge Pike, Tintwistle Knar, Roe Cross, etc., in Staftbrdshire, etc., also 

 Derwent Edge. It occupies the moorlands between the Wigan and Burnley coal- 

 fields, in Lancashire. The Shale Grit, so named by J. Farey, and subsequently 

 known as the Voredale Grit, is now placed with the Millstone Grit by Prof. A. 

 H. Green. ^ The First Grit or Rough Rock is well seen in the Stannedge quarries, 

 near Chesterfield ; also at Houghton Towers, between Preston and Blackburn. 

 The Sabden shales near Preston contain thin beds of limestone \\ith encrinites. 

 The Henclouds and Leek Roaches are rocks near Leek, which are formed of the 

 Third Grit. The Chatsworth and Rivelin Grit is placed in the lower part of 

 the Middle Grits (.Third Grit). The Pendle Hill Grit occurs locally at the 

 base of the Millstone Grit, in Lancashire, and is equivalent to the Voredale 

 Grit, the beds in this position having formerly been grouped with the Voredale 

 Rocks. (See p. i66.) 



In Lancashire the IMillstone Grit contains thin coals (Brooks- 

 bottom coals) in the shales above the Third Grit. It is estimated 

 to have a thickness of from 3500 to 5000 feet. 



Near Oswestrv the beds consist of white and buff sandstones, with 

 coarse pebbly beds.- 



The Plumpton (Plompton) or Knaresborough Grits, and certain 

 red beds near Spofforth and Cayton Gill, at one time grouped with 

 the Permian, have proved to belong to the IMillstone Grit, being 

 stained by infiltration from New Red rocks. ^ The Plumpton grits, 

 however, owe their colour in part to fragments of red felspar con- 

 tained in them. 



The Cayton Gill Beds, according to INIr. W. H. Hudleston, con- 

 stitute a fossiliferous horizon at the base of the Plumpton Grits 

 on both sides of the Harrogate anticlinal. They yield Pivducius 

 semi ret ictilatus, Streptorhynchus crenislria, FtncsicUa, joints of Encri- 

 nites, etc.* 



The Brimham Rocks near Pateley Bridge, and Birk Crag near 

 Harrogate, are formed of IMillstone Grit, and well illustrate 

 the action of atmospheric disintegration on rocks of unequal 

 hardness. 



The Ilkley Crags near Bradford, and Ryeloaf Hill near Settle, 

 are also formed of Millstone Grit. 



In North Flintshire the IMillstone Grit rests directly on the 

 Carboniferous Limestone. It consists of chert beds, having a 

 thickness of 350 feet or more. This chert, as remarked by IMr. 

 A. Strahan, is probably a siliceous sediment of extreme fineness, 

 and it passes in the neighbourhood of Holywell and further south 

 into a fine-grained quartzose sandstone with bands of chert, and 

 then into a grit with quartz pebbles.* (See also p. 165.) 



^ Geol. N. Derbyshire (Geol. Survey), edit. 2. 



^ D. C. Davies, P. Geol. Assoc, iv. 564. 



3 J. C. Ward, Q. J. xxv. 294. Mr. E. W. Binney and the Rev. J. S. 

 Tute have expressed similar views concerning the Carboniferous age of these 

 red rocks. 



* P. Geol. Assoc, vii. 426 ; see also C. F. Strangways, Geol. Harrogate (Geol. 

 Survey). 



* Geology of Rhyl, etc. (Geol. Survey), p. iS. 



