In the Ribble Valley and at Bowland Forest, the Yoredale Rocks admit of three great divisions (Geo!. Survey) as follows:

1. Upper Yoredale Grit, consisting of grits and beds of sandy shale, also conglomerate, 1,000 to 1,200 feet.

2. Bowland Shales, black and grey bituminous shales, with beds of sandstone and limestone, 600 to 700 feet.

3. Lower Yoredale Grit, consisting of grits, sandstones, shales, and ironstones, having a thickness of about 600 feet.

In Derbyshire, Mam Tor, or the 'Shivering Mountain,' is composed of rocks belonging to the Yoredale series, which is there sometimes called the Limestone shale. It forms a wet soil, causing landslips of great extent, beneath the Millstone Grit summits.

At Harrogate beds formerly classed with the Millstone Grit have been more recently placed in the Yoredale series by Prof. Phillips: these include the Spofforth Haggs roadstone (10 feet), the Follifoot coal-grit (30 feet), the Almes Cliff grit (50 feet), the Harrogate Tunnel sandstones (20 feet), and the Harrogate roadstone (50 feet): interstratified with these beds are shales, some containing Stigmaria.

At Clifton between the Carboniferous Limestone and Millstone Grit, there is an alternation of limestones, shales, and sandstones, 300 or 400 feet in thickness, sometimes classed as the Upper Limestone Shale.

In Leicestershire and Monmouthshire the upper beds of the Carboniferous Limestone consist of limestones alternating with dark shales.

Among the fossils of the Yoredale series, occurring chiefly in the limestones, are Orthoceras, Goniatites sphe

ricus, Posidonomya, Productus.

Stigmaria, &c., are likewise met with.

Fossil plants, such as

The Yoredale rocks present no very special palæontological features; they comprise beds of marine and estuarine origin, and some that exhibit fluviatile and terrestrial conditions.

Bitumen occurs at Clithero. The lead-mines of Alston Moor, Weardale, Arkendale, are situated in these rocks.

The fine-grained micaceous grit-stones of the lower series are much used for building- and paving purposes, as at Bakewell Edge, &c. The thin coals, as Prof. Phillips observes, are not worth the expense of the fruitless trials in search of

them.

Rotten-stone, supposed to be due to the removal of the calcareous portion from cherty limestone, is met with near Ashford and Bakewell in Derbyshire.

The Bishopley Limestone, quarried near Frosterley, Durham, and the Gilling stone, quarried near Gilling, Yorkshire, are limestones of economic value in the Yoredale series.

UPPER CARBONIFEROUS.

MILLSTONE GRIT.

This formation consists of coarse sandstones, grits, shales, and conglomerate, with occasional seams of coal. It generally crops out along the margin of our coal-fields, and indeed forms the immediate foundation upon which they rest; and from the circumstance of its being below the Coal-measures, and containing in the south-west of England and South Wales no valuable coal-seams, it has in those districts been termed the Farewell Rock.'

The fossils of the Millstone Grit are few; mollusca are confined to a few limited horizons, but plant remains are not

uncommon.

At Alston Moor the Millstone Grit consists of alternations of sandstones, shales with ironstone and coal, attaining a thickness of at least 409 feet. In Swaledale the series embraces coarse gritstones, shales, sandstones, coal, and local interpolations of limestone and chert, having a thickness of 800 feet. At Wensleydale the series is very similar in character, and is about 700 feet in thickness. At Ingleborough and Penyghent the series is but 260 feet in thickness. (Phillips.)

The Brimham Rocks, Pateley Bridge, near Harrogate, are formed of Millstone Grit. They well illustrate the action of atmospheric disintegration on rocks of unequal hardness.

FIG. 9.-The Idol Rock, Brimham. Pulpit Rocks to the right.

The Plumpton rocks (Knaresborough grits), once believed by some geologists to be Permian, have recently been determined by Mr. J. C. Ward to be Millstone Grit.

Near Bradford the Ilkley Crags are formed of Millstone Grit; at Horsforth, flags are worked, and the upper beds (80 to 180 feet in thickness) yield the famous Yorkshire stone'

1 This woodcut is borrowed from Mackintosh's Scenery of England and Wales, p. 122.

used for building and other purposes.

At Gatherly Moor,

near Richmond, the Millstone Grit is quarried.

In the Escarpment of the Rough Rock near Bury, north of Rochdale, is the Feather Edge Coal, which has been extensively mined.

The following divisions of the Millstone Grit in Yorkshire and Derbyshire have been determined by the Geological Survey:

Middle Grits and Shales (Third Grit)

Shales and sandstones [Sabden Valley shales (1,500

Feet
50 to 60

60 to 100

75 to 150

100 to 175

300 to 500

500 to 700

The several divisions are not always represented, and they are subject to great changes in thickness.

The name Kinder Scout Grit was proposed by Messrs. Hull and Green; the rock forins the high table-land of Kinder Scout, in the Peak country, where the disintegration of the quartzose conglomerate yields numbers of quartz pebbles.

In Lancashire the Millstone Grit contains thin coals, and is estimated to have a thickness of from 3,500 to 5,000 feet.

1 This section is borrowed from Mackintosh's Scenery of England and Wales, p. 214.

In Leicestershire the thickness is 50 feet; it consists in the lower part of quartzose conglomerate, in the middle of grits worked for millstones, troughs, and building-purposes, and in the upper part of grits and shales, which pass by almost insensible gradations into the Coal-Measures above. Sections of this passage are mentioned by Prof. Ansted as visible near Castle Donington and Thringstone.

In Monmouthshire the beds consist of hard sandstone and conglomerate, with shale partings, and have a thickness of 330 feet. In the Forest of Dean the thickness is 450 feet.

In the southern part of Glamorganshire, the Millstone Grit forms elevated ridges of quartzose conglomerate and grit, large blocks of which lie strewn over the surface of the country.

In the Mendip country sections are rarely seen the beds are generally represented by close-grained quartzite with ironstained spots.

In Devonshire the Millstone Grit has not been distinguished, although no doubt represented in the lower part of the Culm-Measures,-perhaps by the Coddon Hill Grits.

The Millstone Grit is generally very unproductive and barren, so far as the soil is concerned.

Good building-stones are furnished by the series in Yorkshire, Lancashire, and Derbyshire.

Amongst the stones of local repute may be mentioned the Prudham stone, near Hexham; the Shawbank stone, Stenton Quarries, Barnard Castle, Durham (building); Bramley Fall Grit, Horsforth sandstone, near Leeds; Delph stone, Pule Hill Grit, Yorks.; Parbold stone, Haslingden Flags, Lancashire; the stone from Duffield Bank Quarry, Derby; Darley Dale sandstone, Bakewell; Sydnope stone, near Matlock; Chevin stone, near Belper; Hartshill stone (hard quartzose rocks, altered Millstone Grit), near Nuneaton, Warwick.