Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/735

Rh OE THE CARBONIFEROUS SERIES. 631 (8) Warwickshire Coal-field. feet. Stage G. — Sandstones and shales, with a band of limestone near the base, with Siyirorbis carbonarius* 60 Stage F. — Sandstones, shales, coals, &c 1400 Stage E. — Sandstones, shales, &c, with sheets of intrusive basalt 1500 Stage D. Millstone Grit. — Converted into quartzite by sheets of intrusive trap 500 Lower Stages C, B, & A not represented. The above concludes all that is necessary in order to show the relations of the beds in the northern group of coal-fields of England and Wales. With regard to the southern group, it will probably be sufficient if we notice the Sections of Somersetshire and South Wales. (9) The Somersetshire (or Bristol) Coal-field. It is very doubtful whether any representatives of the Stage G occur either here or in South Wales. It is true that there is a local subdivision of the Coal-measures into three stages in both districts, of which the " Pennant Grit " forms the central member. This arrangement is convenient for local purposes ; but the Pennant grit can only be considered as an exceptionally thick group of sandstones interposed amongst the Middle Coal-measures (Stage F), and not as forming a central group corresponding to Stage F in other districts. As regards the Lower Coal-measures (Stage E), although this stage is remarkably well represented by its numerous marine fossils around the rim of the South- Wales basin, it is less so in Somersetshire, partly owing to its dislocated or inverted condition along the northern Hanks of the Mendips, and also to the fact that it rarely crops out to the surface, the beds being concealed by Triassic or newer strata. The general section will therefore be somewhat as follows : — Section of the Bristol or Somersetshire Coal-field, feet. Stage G. — Imperfectly represented. Possibly the upper part of the Radstock series, ? Stage F. Middle Coal-measures. — Shales, grits, and coals of the Far- rington, Pennant, and Bedminster series. Fossils : plants, fish, and Anthracosia 4700 Stage E. Lower Coal-measures. — Sandstones, shales, and numerous coals of the Holcombe series (in part) 2000 Stage B.~Millsto7ie Grit (Bristol) 950 Stage C. — Yoredale Shales (thin), 100 Stage B. — Carboniferous Limestone 2S30 Stage A. — Lower Limestone Shale, 100 Old Red Sandstone. Survey (1859). 2t2
 * Mr. Howell, "The Geology of the Warwickshire Coal-field," Mem. Geol.