COAL MEASURES. 173 



Eco7iomic prodiccts, etc. 



Excellent paving- and building-stones are furnished by the Mill- 

 stone Grit in Yorkshire, Lancashire, and Derbyshire. At Horsforth, 

 near Leeds, flags are worked, and the upper beds (80 to 180 feet in 

 thickness) yield the famous ' Yorkshire stone ' used for building 

 and other purposes. 



The massive Kinder Scout Grits furnish blocks for engine-beds, 

 foundations, and reservoir work. The beds are quarried at Eyam 

 Moor, Derwent Edge, etc. The variable beds of the IMiddle Grits 

 yield flagstone, also good building-stone at Beeley and Darley Moors, 

 and Addingham Edge, while the Calliard furnishes excellent road- 

 metal. Flags at the base of the Rough Rock furnish good flag- 

 stones at Haslingden, Entwistle, Edgworth, etc. The Rough Rock 

 is quarried for building-stone : the Bramley Fall quarries near 

 Leeds being noted. 



Near Accrington the Rough Rock yields sand which is dug in places. 



The Cefn Sandstone of P'lintshire contains beds largely used for road-mending, 

 and one bed (the Aqueduct Grit) furnishes good building-stone. Caernarvon 

 Castle was built of this rock. Scythe-stones have been made at the Talacre quarry 

 in Flintshire. 



In the Vale of Neath, the celebrated Dinas fire-bricks are manufactured from 

 sandy beds belonging to the Millstone Grit. The material, known as "Dinas 

 clay," contains 98 per cent, of silica, with traces of alumina, protoxide of iron, 

 lime, potash and soda.' These bricks are used for lining copper-furnaces, etc. 

 The chert beds in the Millstone Grit of Flintshire are quarried at Pentre, near 

 Gronant, for use in the Staffordshire Potteries. 



In the Escarpment of the Rough Rock near Bury, north of Rochdale, is the 

 Feather Edge Coal, which has been extensively mined. Coal has also been worked 

 near Ovingham, in Northumberland. Zinc-ore is worked at the Talacre mine, in 

 Flintshire. 



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

 is concerned, and much of the country occupied by it is moorland. 



COAL MEASURES. 



The term Coal-measures was used by William Smith in 

 18 17, and previously by the Rev. John Michell. No doubt 

 the term had long been in common use. 



The Coal-measures consist of a series of clays and shales, 

 grits, sandstones, and ironstones, characterized by the abund- 

 ance of coal-seams and the general absence of limestones. Of 

 these beds the seams of coal are the most persistent, while 

 the sandstones are often very irregular and inconstant. 



The strata usually occur in what are termed 'Basins' ; that 

 is, in synclinal areas or troughs : these basins, however, are 



1 Percy, Metallurgy, 1S75, p. 146. 



