V. C. Tiling— The Search for Oil. 293 



effect is often noticed in the Coal-Measures -where igneous dykes and 

 sills approach the carbonaceous material. The Carboniferous Lime- 

 stone often contains dark bituminous impregnations and small patches 

 of hard black asphalt, but the elaterite of the Castleton area is of 

 doubtful significance. A. boring at Norton, near Stockton-on-Tees, 

 yielded a small show of oil from shales above the Carboniferous 

 Limestone, and paraffin wax was noted from the same formation at 

 Ladysmith Colliery, Whitehaven. The oil obtained from the 

 Kelham boring near Newark appears to have come from the Mill- 

 stone Grit series. 



Among the Coal-Measures methane is, of course, a well-known 

 material associated with coal-seams, but it is significant rather of 

 a phase of vegetable decomposition than of any necessary association 

 with petroleum. Sometimes this gas escapes at the surface, the old 

 gas spring at Wigan described by Thomas Shirley in 1667 being an 

 interesting example. Liquid petroleum has sometimes been recorded 

 in mines, either as an oily impregnation of the shales or as a slight 

 drip from the roof of a coal-seam. Such instances occur in most of 

 the coalfields, but the quantities of oil are small. Occasionally larger 

 yields have been obtained. At Meirhay Colliery, Longton, North 

 Staffordshire, five tons of oil were produced and refined per week for 

 several years, while the still better-known example at Southgate 

 Colliery, Clowne, yielded about 300 gallons per week. This oil was 

 refined by James Young in 1848, and when the supply ceased 

 attempts were made to distil coal. These led to the retorting of 

 torbanite and eventually to the foundation of the Scotch oil-shale 

 industry. Occasionally oil escapes to the surface of the Coal- 

 Measures, examples being found at Coalport and Pitchford in 

 Shropshire. Still more rarely it impregnates an outcropping porous 

 rock ; the best example occurs at Coalbrookdale. 



Both the Permian and the Trias have afforded a few examples of 

 bitumen ; oil from the Magnesian Limestone and gas from wells in 

 the Trias. The Jurassic clays frequently contain a small amount of 

 bituminous matter. The Calvert boring yielded gas from the Lias 

 clays, while the gas from Heathfield, probably from the Upper 

 Jurassic clays, was used for lighting the local railway station. 

 Among the Cretaceous and Tertiary strata in Britain, evidences of 

 bitumen are exceedingly rare. 



Having briefly enumerated the main indications of bitumen in the 

 British Isles, it will be necessary to discuss their significance. They 

 may be generally summarized as small, even insignificant, and in the 

 rare cases of a somewhat larger yield the supply was quite ephemeral. 

 Now it is not generally realized that bitumen in small quantities is 

 almost universally distributed in nature ; even igneous rocks are 

 not free from the material, and among the marine sediments it is 

 quite common. Hence the mere enumeration of a long list of 

 interesting but minute occurrences of asphalt, oil, and gas in 

 a country like Great Britain, where geological exploration, quarrying, 

 mining, and drilling have accumulated large stores of knowledge of 

 the strata, can hardly be a matter of surprise. The significance of 

 an oil show is not in the seepage itself, but in what it indicates. It 



