South Staffordshire Coalfield.—The Carboniferous rocks of South Staffordshire are arranged in a broad dome about 23 miles in length by 6 in breadth. Their basement beds rest unconformably upon the Silurian around the flanks of the Dudley Hills, and in the neighbourhood of Walsall. Their highest beds dip conformably below the Permian rocks at the southern extremity of the coalfield south of Halesowen, and are overlapped unconformably by the Triassic pebble beds at its northern extremity, in the district of Cannock Chase. The eastern and western boundaries of the coalfield are formed by lines of fault, which have flung down against the Coal Measures the various members of the Permian and the Triassic. The total thickness of the Carboniferous beds is about 1,300 feet, and the normal succession in the central and highest part of the coalfield is as follows:—
Upper Coal Measures.—
2a. Halesowen Sandstone Group, 600 to 800 feet.
2b. Red Coal Measure Clays.
Lower Coal Measures, 500 to 600 feet, containing several excellent coal seams, of which the following are the most important:—
(a.) Brooch Coal, 4 feet.
(b.) Thick Coal, 30 feet.
(c.) Heathen Coal, 3 feet.
(d.) New Mine Coal, 2 to 11 feet.
(e.) Fire Clay Coal, 1 to 14 feet.