A HISTORY OF LANCASHIRE
We are strongly of opinion that the identity of lithological character of these beds with those of the Millstone Grit Series and Lower Coal Measures, coupled with a fauna which is practically the same in all, will eventually result in the old stratigraphical boundaries between them being set aside, and the whole series grouped together, as indeed they ought to be.
Pendle Grit, or 'Upper Yoredale Grit.'—The summit of Pendle Hill is occupied by a massive bed of grit sometimes known as the Pendle Grit. It is a fine-grained sandstone, rarely passing into a conglomerate, and containing much felspar and mica. It has been correlated with 'Farey's Grit' in the Peak district of Derbyshire.[1] Quarries are opened in it on the south side of the Nick of Pendle, where it is seen to contain large ovoid concretions marked with brown and yellow bands. The same beds form the summit of Longridge Fell, and constitute the greater part of the Fells around the Ribble and Hodder basins. It is also to be seen near Mellow, along the north side of Billington Moor, and so on to Whalley.
The occurrence of the massive Pendle Grit on the summit of Pendle has served to protect the latter from suffering so heavily from the effects of denuding agents, which have lowered the surrounding country. That Pendle was subjected to these forces is shown by the deep ice scratchings impressed on the surface of the grit during the glacial period, and still to be seen on a freshly exposed surface.
Probably also, this Sandstone capping was equally effective at a still earlier period, just as it is to-day, now that Pendle rises so grandly out of the surrounding low country to an elevation which can be seen across two score miles of country.
Lying above the Yoredale or Pendle Grit are a series of shales but seldom seen, but where exposed, as in the road between Offa Hill and Stank Top, having a thickness of about 200 feet. Shales and sandstones occupying the same position are seen north of Foulridge.
Above these shales we meet the lowest member of the Millstone Grit Series, known as the Fourth Grit, or Kinder Scout Rock.
MILLSTONE GRIT SERIES
The Millstone Grit Series is extremely well developed in Lancashire, where it forms a well-marked boundary to the Coal Measures on the east and north.
The eastern flanks of the Millstone Grit rise up into the elevated moorland hills which form a natural boundary to Lancashire and Yorkshire.
This region may be rightly regarded as an outlying portion of the Pennine Chain, which runs as an elevated ridge from Derbyshire to the borders of Scotland.
The Millstone Grit of the northern border of the coalfield rises up into a similar range of bare and bleak moorlands, running from a little west of Blackburn to Colne and Skipton, between which places it merges into the hill ranges of the eastern side; on the western side, the series extends northwards by Longridge and Great Mitton.
South of a line drawn from Blackburn to the Holme Valley between Burnley and Todmorden, the coalfield encloses two other areas of Millstone Grit, the most westerly forming Anglezark Moor, and the easterly the hill district of Rossendale. In the latter area the grits form what is known as the 'Rossendale Anticlinal.'
North of a line drawn from Garstang to Long Preston is an extensive area of Millstone Grit the westerly border of which reaches the coastline in the neighbourhood of Heysham, where it forms a line of low cliffs, upon which Heysham Church is built. From Heysham the grits pass in a northerly direction to a little east of Kirkby Lonsdale. Skirting the whole of the comparatively unimportant Ingleton Coalfield, except on the north-eastern side, they swell out into Yorkshire as far as Clapham and by Giggleswick. Within this area are included the Bleasdale Moors and the Forest of Bowland with its two inliers of Carboniferous Limestone. Throughout the Lancashire coalfield wherever the Millstone Grit occurs, the surface features are of a remarkable character. The moorlands are everywhere bare, lofty hills, rising in many places to heights of 1,200-1,900 feet, and supporting a sparse vegetation of heather, cotton grass, &c., whilst extensive areas are covered with thick beds of peat. The hill sides are often steeply scarped, and stand out as bold bluffs of grit, sometimes fantastically weathered, and deeply indented along their margins by steep narrow gullies, usually termed 'cloughs,' which form the beds of mountain streams. The cloughs, or ravines, run upwards into the hills, where they finally disappear on the moorland. For the greater part of their length, however, they present features widely different from those of the hills which enclose them.
The steeply sloping sides are usually formed in their lower half of scree material derived from the weathering of the sandstones and shales above, and on the material thus accumulated, vegetation
- ↑ R. H. Tiddeman, in 'Geology of the Burnley Coalfield,' Mem. Geol. Survey, p. 23.
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