Reviews — Geological Survey — Summary of Progress. 375 



strongly opposed by Dr. Wheelton Hind and Mr. J. T. Stobbs (Gteol. 

 Mag. 1906). Their paper is mentioned in a footnote, but their 

 advice does not appear to have been taken. No satisfactory evidence, 

 however, is given for the continued classification of the strata termed 

 Millstone Grit, nor of the Gwespyr Sandstone, etc. The red or 

 purple marls overlying the Middle Coal-measures, and termed the 

 Ruabon Marls, are estimated to attain a thickness of about 900 feet : 

 of these the lower beds are worked for bricks and terra-cotta clay. 

 The succeeding Coed-yr-allt group consists of sandstones and shales 

 with Spirorhis-livnes^toue?, ; and the highest division, termed the 

 Ebbistock Beds, is a thick series of red and purple sandstones with 

 conglomeratic bands and much I'ed marl. 



In what is termed the Warwickshire district, which includes 

 South Staffordshire, attention lias been given to the Cambrian and 

 Silurian rocks, and more particularly to the Coal-fields of South 

 Staffordshire and North Warwickshire. In the last-named coal-field 

 the succession is given as follows: — 



Upper Red Marls and Sandstones. (' Permian' on old map.) 



Upper Grey Measures. Halesowen Sandstone Series. 



Lower Red ilarls and Espley rocks. 



Lower Grey Measures, in which alone workable coal-seams occur. 



The Espley rocks are described as sometimes bright green in colour, 

 and composed of angular chips of green shale, derived as scree 

 material from the Cambrian Shales of Dosthill. 



Breccia-beds or conglomerates with some pebbles, but mostly with 

 angular fragments of limestone, are described as occurring above the 

 upper part of the ' Permian ' and below the Bunter pebble-beds ; but 

 there is at present considerable doubt about the grouping of these 

 and some other Red rocks of pre-Triassic age. 



In the London and South-Eastern district work has been carried on 

 at Aylesbury and over the Chiltern Hills to Rickmansworth, and in 

 the 13agshot areas about Ascot and Weybridge. 



In Scotland the survey has been prosecuted in the "West Highland 

 district, on the gneiss and newer granites of Morvern and on the 

 Tertiary igneous rocks of Mull; and in the North and Central High- 

 land district among the metamorphic and associated igneous rocks of 

 Ben Armiue in East Sutherland and those of parts of Perth and 

 Inverness. Revisions of the areas of coal-fields were made in the 

 districts of Carluke, East Kilbride, and Douglas, and in those of 

 Shotts and Fauldhouse. The crumpling in certain sandstones of the 

 Millstone Grit is attributed to the decay of buried tree-trunks. In 

 another area an illustration is given of certain ' wants ' (or lack of 

 continuity) in coal-seams adjacent to a fault ; and the subject recalls 

 to mind Dr. R. L. Jack's paper " On ' Wants' in Ironstone Seams" 

 (Geol. Mag. 1871, p. 388). 



In the record of palseontological work some interesting remarks are 

 made on the forms of Gryphcea in the Lower Lias, a subject to which 

 the late John Jones, of Gloucester, gave great attention and illustrated 

 in quarto plates. Important records of Liassic and Oolitic fossils 

 from Mull and from marine Upper Carboniferous beds in Central 

 Scotland are also given. In the Appendix Dr. A. Strahan records 



