REMARKS ON THE COAL DISTRICT OF SOUTH LANCASHIRE. BY JAMES HEYWOOD, F.R.S., F.G.S. (Read December 29th, 1837.) CARBONIFEROUS rocks have long formed an interesting subject of mining investigation in the county of Lancaster, and facts relating to the Geology of this district are continually discovered, by the researches of mining industry, and by the observations of local inquirers. Gritstone hills compose the Eastern boundary of the Lancashire coal district, separating the coal fields of Yorkshire and Lancashire from each other.* Gritstone strata also form the Northern boundary of the district, and on the North-East of Blackburn, in North Lancashire, steeply inclined beds of coal, termed "rearing mines," are found, * See the accompanying Map of the Coal District of South Lancashire. overlying the gritstone rocks of the Northern boundary. Red sandstone strata occur three miles to the South-West of Blackburn, at Feniscowles-bridge; and the red sandstone formation may be subsequently traced, with its associated rocks, on the Western and Southern limits of the Lancashire coal district. A remarkable circumstance occasionally attends the junction of the red sandstone formation with the coal measures of South Lancashire. Long promontories of red sandstone are there found to divide, to a considerable depth, the strata of the coal measures; they sometimes narrow gradually towards a point, nearly in an acute angle, within the coal formation, and then spread out, in the opposite direction, beyond the limits of the carboniferous rocks. Several of these promontories of red sandstone have been observed on the Southern boundary of the Lancashire coal district, in the neighbourhood of Eccleston, and Worsley, in South Lancashire, but the principal promontory of red sandstone which has yet been discovered, stretches out, in a South-Easterly direction, along the valley of the river Irwell, for about seven miles, from Ringley to Manchester. The Western side of this red sandstone promontory of the valley of the Irwell, is bounded by the rocks of the coal formation, which are supposed to be thrown down, below the red sandstone, by a fault of 1000 yards of downcast to the North-East: but the Eastern side of the promontory is little known, being generally concealed by the sand and gravel beds, which frequently overlie the sandstone rocks, on both sides of the valley of the Irwell. Between Ringley and Clifton, the fault, on the Western side of the red rock promontory, is visible, as it crosses the bed of the river Irwell, and its direction is North-West by West in that locality. South of Clifton, red sandstone may be traced on the bed of the river Irwell, near Kersal Moor, Castle Irwell, and under the bridges between Manchester and Salford. On the Eastern side of Manchester, coal is found at Bradford, and the red sandstone rock occurs again to the East of the Bradford collieries: coal is afterwards found above Bank-bridge, on the river Medlock, in the same vicinity; and the carboniferous rocks are then continued without interruption, to the gritstone hills on the Eastern boundary of the district, beyond Ashton and Oldham. At Ardwick, on the Eastern side of Manchester, and very near to the town, several beds of limestone are found,* interstratified with beds of carboniferous shale: the inclination of the Ardwick limestone is conformable to that of the carboniferous strata, and tends towards the South West. Nine miles to the West of Manchester, at Bedford, near Leigh, strata of Magnesian limestone occur, which are not conformable to the carboniferous strata in that neighbourhood. From observations made at Bedford, near Leigh, by the late Dr. Phillips, of Manchester, and communicated by that able inquirer to the author of this paper, it appears, that the strata of the Magnesian limestone at Bedford tend to the South-East, and *All beds of limestone are coloured blue, in the accompanying Map of the Coal District. that the red sandstone rocks of the same locality dip to the East, with a slight inclination towards the South, while the carboniferous gritstone, against which the Magnesian limestone there rests, dips rapidly to the South-West; hence the carboniferous grit rocks of Bedford are manifestly unconformable, both to the red sandstone, and to the Magnesian limestone of that portion of the South Lancashire coal district. Several parallel faults occur in the coal district, on the Northern and North-Western side of Manchester, which have a North-Westerly direction, parallel to the great red rock fault of the valley of the Irwell, and which give an appearance of great regularity to the divisions of this portion of the coal district. Two of these parallel faults were noticed by a scientific agent, surveying for the author, on the banks of the river Irwell, at Brandlesholme, North of Bury, in South Lancashire. The first of the two faults was observed to separate the strata of the dark ferruginous shale of that neighbourhood, from the carboniferous sandstone, and to change the inclination of the strata adjacent to it on both sides. Above the fault, the inclina |