PHOCEEDrNGS OF THE GEOLOGICAL SOCLETY. . IO7 



2. " Evidence of the Action of Land-ice at Great Crosby, Lanca- 

 shire." By T. Mellard Eeade, Esq., F.K.S. 



3. " The North-Wales and Shrewsbury Coal-fields." By D. C. 

 Davies, Esq., E.G.S. 



[Abstract *.] 



After discussing the origin of Coal-beds, and the causes of their 

 rariation in structure and quality, the author proceeded to describe 

 the North Wales and Shrewsbury Coal-field, which consists of three 

 parts: — (1) The Shrewsbury field south of the Severn, exclusively 

 composed of Upper Coal-measures ; (2) the tracts north of the 

 Severn, extending from near Oswestry to north of Wrexham ; and 

 (3) the Elintshire Coal-field. The first and second are separated 

 from each other by the alluvial plain of the Severn and Yyrnwy, 

 and the second and third by the Great Bala and Yule faults. 



Some remarks on the scenery of the Welsh border-land followed, 

 and then a general section of the Carboniferous system,as developed 

 in the country described, was given, the Permian beds being in- 

 cluded, as the Author considered them the upper portion of one 

 great division of Palaeozoic time. The section was as follows, with 

 the maximum thickness of each subdivision : — 



Thickness in yards. 



1. Dark red Sandstone 210 "] 



2. Iftou or St. Martin's Coal-measures '''^ I P * 590 a'd- 



3. Eed marls with calcareous matter 180 j ® ' ^ 



4. Green rocks and Conglomerates 125 J 



5. Upper Coal-measures 80^ 



6. Cefn rock to Cefn coal 100 | ^ -, 



7. Cefn coal to Lower yard-coal 270 }- ^^''^g g^'^'^^'^J' 



8. Lower yard-coal to Chwarcle coal 80 | ^ ' 



9. Chwarcle coal to Millstone Grit 136 J 



1255 yards. 



A detailed description of the strata was next given, beginning 

 with the lowest, together with details of each coal-seam as worked 

 in various parts of the field. After describing the beds from the 

 Millstone Grit to the Cefn rock in the North-Wales coal-field, the 

 Author proceeded to notice the Upper Coal-measures and Permian 

 strata in the Shrewsburj' area, and showed that no break exists between 

 the two, the former passing gradually into the latter. He then 

 discussed the probability of Lower Coal-measures existing beneath 

 the upper beds near Shrewsbury, and showed from sections that the 

 existence of the lower measures might be anticipated. A similar 

 inquiry as to the presence of the Coal-measures beneath the New 

 Eed Sandstone of the Yale of Clwyd should also, in the Author's 

 opinion, be answered in the afiirmative. 



The organic remains found in the different beds were briefly 

 noticed, and then the faults of the district were discussed at some 



* 



This paper has been withdrawn by permission of the Council. 



