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 GEOLOGY The southern fringe of the coalfield might be described as a hummocky country, a series of shallow river valleys separated by low, broadly rounded hills. It is along this southern fringe that the rich Middle Coal Measures chiefly occur, only a few isolated patches being found in the northern half, the chief of which is known as the Burnley Coal Basin. The large cotton and iron manufacturing towns of Lancashire lie along the lower parts of the valley systems, the flanks of the moorlands being occupied by grazing farms, and the crests by quarries. On the south and west of the Lancashire Coalfield is the great Cheshire and west Lancashire plain of Triassic rocks. The district is almost entirely agricultural, flat and monotonous. Mining History. — Whether coal mining was practised in Lancashire by the ancient Britons is a point upon which there is no certain evidence. Previous to the time of the Roman occupation, the county was largely forests and swamps, and the ease with which wood could be obtained discounts any theory of coal working by the Britons. That coal was mined and used as fuel by the Romans is very probable, for Whittaker, the Lancashire historian, has recorded that the evidence of a large coal fire, and an abundance of ashes and scoriae were dug up in the ' Castle Field ' in the Roman centre of Mancunium or Manchester.i Whether coal was used in Lancashire by the Saxons is not known. That the coal was taken out at a remote period has been proved by the finding of old workings and old implements of mining, such as oaken shovels tipped with iron, etc. Coal was mined in the Burnley area in the time of Henry VIIL,* but only with the com- mencement of the nineteenth century did mining become important, its progress being synchronous with the development of woollen, iron, and cotton industries. LOWER COAL MEASURES These measures bound the northern side of the South Lancashire Coalfield, and send three arms northwards through the Millstone Grit country to the Burnley Coalfield, which they com- pletely encircle. Immediately to the south of the latter coalfield they cover a tract of country fifteen miles long from east to west, and three to five miles broad from north to south. The Lower Coal Measures include all the beds lying between the Upper Rough Rock of the Millstone Grit Series and the floor of the Arley Mine (also known as 'Little Delf at St. Helens, ' Riley Mine ' at Bolton, and ' Dogstone Mine ' at Bury). They consist mainly of shales, with thin bands of nodular ironstone, sandstones and thin coals, reaching in all a thickness of 1,200 feet along the line of the ' Rossendale Anticlinal.' Not more than six coal seams are present in the series, the total thickness rarely exceeding ten feet. The accompanying generalized section in the Rossendale area serves to illustrate the position and thickness of the seams : — ft. in. ft. in. Pasture, Bassey and other thin coals. 431 o Shales and Grits 20 o Upper Mountain Mine Coal ... 16 Lower Foot Mine Coal .... 08 Shales 360 Strata 40 o Fireclay Coal 02 Bassey or Salts Mine Coal. . . . 2 to 3 o Strata 56 o Shales and Grits 100 o Upper Foot Mine First Coal 010 Mountain Four Feet Mine where they unite. Coal .... 08 Rough Rock Shales 30 Lower Mountain or Ganister Mine Coal .... 2 The coal seams are frequently termed ' Mountain Mines,' owing to their general ocurrence on the high ground. But three are of commercial importance, viz. the ' Gannister,' ' Yard ' or ' Lower Mountain Mine,' the ' Upper Foot ' or ' Bullion Mine,' and the ' Upper Mountain Mine.' The ' Bassey ' or ' Salts Mine ' is a very impure coal and not much used. It is worked to some extent in the Blackburn area. The Upper Mountain Mine and the Gannister seam have been largely worked by adits and shafts to supply the wants of the numerous cotton manufacturing towns of Lancashire, and are still largely used. The chief coal supply from the Lower Coal Measures will in the future, have to be drawn from a four-foot seam formed by a union of the 1 Hislory of Manchester, i. 301. ^ Hull's Coal Fields of Great Britain, ed. 4, 1891, p. 220. 13