Correspondence — David Woolacott. 479 



O O IEt R IE S :P O IDT ID E 3ST a :e _ 



EECENT PAPERS ON THE DURHAM COALFIELD. 



Sik, — In the Geological Magazine of July there is a letter from 



Mr. J. T. Stobbs criticizing two papers which appeared in the April 



and May numbers. I desire to give a short reply to this letter. 



The chief reason for publishing the paper dealing with the borings 



at Cotefield Close and Sheraton was that the cores gave information 



regarding an almost totally unknown facies of the Middle Magnesian 



Limestone, and therefore more stress was laid on the description of 



the Permian rocks than on those of the Coal-measures, which were 



only dealt with in a general manner. It may, however, be possible 



to deal with these and other sections in the latter strata on a subsequent 



occasion. I came to the conclusion after consultation with the 



mining engineer that the boring at Cotefield Close had entered the 



Coal-measures beneath the Erockwell Seam from comparison with 



other sections, from the character of the strata and from the structure 



of the country. It is true that the coals in the Ganister Series have 



been worked in the western part of the coalfield, but over a large 



portion of it the exact nature of the strata occurring beneath the 



Erockwell Seam are not well known. The coal-seams in these beds 



are not constant, are thin, and seldom worked. There are a few 



borings in the Ganister Series, but the strata have never been 



properly correlated or described. The late Professor Lebour wrote 



some vears ago, "As a consequence of the small importance of the 



coal-seams known to exist in the Ganister Beds not many detailed 



sections of sinkings and borings can be referred to for details in the 



strata." These words are still true and especially true for the 



deeper parts of the coalfield beneath the Magnesian Limestone of 



Durham. Further, from a pakeontological standpoint, not only the 



Ganister Series but the whole of the Coal-measures of Northumberland 



and Durham may be said to be little known. No exact knowledge 



of the zones in this coalfield has yet been obtained. Aviculopecten 



{Pterinopecten') papyraceus, Carbonicola robusta, and Anthracomya 



Phillipsi appear to be confined to definite horizons, but there still 



remains much work to be done on the palaeontology of these rocks. 



I think that when the Coal-measures of the Northern Coalfield are 



zoned it will be found that Aviculopecten papyraceus is confined to the 



Ganister Series in this area. My note regarding it may not be found 



to be so quaint as Mr. Stobbs supposes. I used the generic name 



Aviculopecten because I was referring to Professor Lebour's discovery 



of this fossil. If Mr. Stobbs knows anyone who is thoroughly 



acquainted with the Ganister Series of Northumberland and Durham 



and could prevail upon him to write an account of these beds I am 



sure geologists would feel indebted to him. 



In the paper " The highest Coal-measures in the Durham Coalfield ' r 

 an attempt was made to give an exact description (which had never 

 been done) of the section in which Anthracomya Phillipsi occurs ; 

 also to show the relation of Ancylus Vinti, Kirkby {Carbonicola 

 Vinti, Hind), to Anthracomya Phillipsi as they occur associated 

 together in this section, and to give as complete a list of the fauna 

 and flora as possible. Dr. Trechmann and I certainly never thought 



