Vol. 62.] LOWEK CAEBONIFEROTTS OF CANNOCK CHASE. 523 



24. On the Occttrkence of Limestone of the Lower Carboniferous 

 SePvIes in the Cannock-Chase Portion of the South Stafford- 

 shire Coalfield. By George Marmaduke Cockin, P.G.S. 

 (Read March 7th, 1906.) 



The South Staffordshire Coalfield embraces a district 26 miles in 

 length, and includes the southern portion of Staffordshire as well 

 as portions of Worcestershire, Warwickshire, and Shropshire. 

 Over the southern portion of this coalfield the Coal-Measures rest 

 directly upon the Silurian limestone. This is known to be the case 

 as far north as the Great Bentley Fault, north of which a deep 

 sinking and borehole at No. 2 pit, Cannock-Chase Colliery, proved a 

 thickness of 1212 feet of Coal-Measures below the Deep Coal-Seam, 

 succeeded by 102 feet of limestone-rock, said to be Silurian 

 limestone. 



It has been thought up to the present time, in the absence of any 

 proof to the contrary, that the Lower Carboniferous rocks are 

 altogether wanting in this area. Jukes, in his Geological Survey 

 Memoir on the South Staffordshire Coalfield, 2nd ed. (1859) p. xii, 

 says : — 



' These vast formations of Old Red Sandstone and Carboniferous Limestone 

 (to say nothing of the lower part of the Coal-Measure Series or Millstone Grit) 

 are altogether absent in South Staffordshire, neither is there the slightest 

 reason for supposing that any part of them ever existed in that district.' 



Dr. Charles Lapworth & Mr. A. Sopwith, in Part III of the 

 Heport of the Royal Commission on Coal-Supplies, published in 

 1905, make the following statement : — 



' Neither Carboniferous Limestone nor Millstone Grit are known to occur 

 within the limits of the South Staffordshire Coalfield. The oldest beds yet 

 recognized are certain Ganister-like strata associated with the deepest Coal- 

 Measures in the borings in Cannock Chase. In the neighbourhood of Walsall 

 and Dudley the basement Coal-Measures lie at once unconibrmably upon the 

 Silurian rocks; and this also appears to be the case somewhat farther north, 

 as shown in the boring at No. 2 Pit, Cannock-Chase Colliery. Elsewhere in 

 the Cannock-Chase area proper, the base of the South Staffordshire Coal- 

 Measures has not yet been proved.' 



Over 30 years ago a shaft was sunk at No. 1 Pair Oak, about 

 5 miles north of the boring at No. 2 Pit, Cannock-Chase Colliery. 

 No workable seam of coal was found at No. 1 Pair Oak in the 975 

 feet of strata sunk and bored through. The coal found consisted 

 of a seam 3 inches thick at a depth of 420 feet, and another half 

 an inch thick at a depth of 567 feet. 



The failure to find the workable seams of the district may be 

 attributed to the fact that the Coal-Measures at and above the 

 horizon of the Deep Coal-Seam have been denuded over an area 

 shown by shaded lines in fig. 1 (p. 521). Afterwards a pair of shafts, 

 called No. 2 Fair Oak, were sunk 800 yards distant, and excellent 

 coal of normal thickness was there found, and worked to a consider- 

 able extent. The shaft at No. 1 Pit was 15 feet in diameter, and was 



