498 STEVENSON— INTERRELATIONS OF FOSSIL FUELS. ■ 



Series of Gibson, consists of the Keele, Newcastle and Etruria Marl 

 groups. The Keele is equivalent to the lower part of the Permian 

 of South Staffordshire while the other groups answer to the Hale- 

 sowen sandstones and Red Coal Measures Clays of that field. The 

 Keele is the Radstockian of Kidston and the other groups form his 

 Staffordian. The total thickness is 2,200 feet. The Grey Series is 

 grouped into Black Band, Middle and Lower Coal Measures with 

 thickness of about 5,600 feet. The Millstone Grit and the Lower 

 Carboniferous, which are reached at the northern side of the field, 

 are without economic interest. 



The Keele consists of red sandstones and marls, which are easily 

 distinguished from the Etruria Clays and from those which occur at 

 various horizons in the Middle and Lower Coal Measures. The 

 Newcastle group, largely sandstone, contains four thin coals, but 

 Keele and Etruria are barren. 



The Black Band, only 400 feet thick, has three or more coals 

 associated with the valuable deposits of black band, but the impor- 

 tant seams are in the Middle Coal Measures, there being 13 of work- 

 able thickness and yielding good coal. Most of them average almost 

 6 feet, seldom reaching 8 feet. Several workable seams are in the 

 Lower Measures. In greatest part, the coals are steam or house 

 fuels, but as they approach the anticline or western boundary of the 

 field, they often change into coking and gas coal. 



Marine fossils have been obtained from 9 horizons, the bands 

 being distributed in the column from base of the Coal Measures up 

 to within 700 feet of Black Band. The Keele group has 3 horizons, 

 from which Spirorbis has been obtained ; these horizons have been 

 recognized in deposits overlying the Halesowen Sandstones in South 

 Staffordshire. 



The Lancashire Coalfield. — This is one of the most important in 

 England. Bolton^°° gave a summary description of it in 1897, util- 

 izing results of studies by himself and earlier observers. The Per- 

 mian deposits in the Pendle range rest on upturned and denuded 

 edges of Coal Measures and pass beyond them to the Millstone Grit. 



The Upper Coal Measures, best shown in the Manchester area, 



100 H. Bolton, "The Lancashire Coal Field," Trans. N. Y. Acad. Sci., 

 Vol. XVI., 1897, pp. 227-239. 



