78 Geological Society. 



nearly a straight line from north to south, commencing at the Grey- 

 hound Pit, near Oakengates Tunnel of the Shrewsbury and Bir- 

 mingham Railway, and terminating at John Anstice and Co.'s 

 Halesfield Pits near Madely. Particular reference was made to the 

 explanation of the nature of the Great East or Symon Fault. The 

 author commenced making his observations on the Malinslee and 

 Stirchlee Royalties in 1843 ; and in 1845 he came to the conclusion 

 that what the miners termed in this locality the " Symon Fault," 

 that is the successive dying out of certain coal-seams, ironstones, 

 &c. at various depths underground, was due to an old denudation 

 which had produced an inclined surface at the expense of some of 

 the beds before the upper measures were deposited. Having obtained, 

 in course of time, correct sections of several pits situated in the 

 N.-S. line above mentioned, the author, taking the " Little Flint " 

 (the lowest workable coal) as a base-line, plotted the several shifted 

 segments of the coal-field in a vertical plan, and thus restored the 

 original outline of the denuded area (one side of a valley) as seen in 

 a transverse section. Six sinkings in the N.-S. line having indi- 

 cated the successive disappearance of five workable coal-beds in a 

 distance of 2484 yards, a seventh pit, 2000 yards further south, was 

 found to yield all the coals again ; and the author thinks that between 

 the 6th (the Grange) and the 7th (Halesfield) pit the coals re-occur 

 successively on the opposite side of the old valley of denudation, and 

 that they may here be sought for and worked advantageously. The 

 line of the old valley of denudation apparently strikes the Great East 

 fault, as laid down on the Geological Survey Map, at a considerable 

 angle. 



2. " On the Occurrence of Cyrena fluminalis associated with Ma- 

 rine Shells in Sand and Gravel above the Boulder-clay at Kelsey Hill 

 near Hull." By Joseph Prestwich, Esq., F.R.S., Treas.G.S. &c. 



The author's observations tended to show that the Cyrena flumi- 

 nails, instead of being limited, in its occurrence, to beds beneath the 

 Boulder-clay (under which circumstance it is found in Norfolk), oc- 

 curs in deposits of newer date, and that the argument, that the 

 well-known beds at Grays, in Essex, are older than the Boulder- 

 clay, depending much on the presence of this shell, would lose much 

 of its force if this Cyrena were proved to belong also to the newer 

 geological horizon. The question is now the more important, as this 

 shell has been found by Mr. Prestwich in the beds that contain flint 

 implements at Abbeville. 



The author proceeded to show that some gravels and sands near 

 Hull in Yorkshire, formerly described by Professor Phillips, contain 

 abundance of the Cyrena fluminalis, associated with twenty-two 

 species of marine shells, two of which have Arctic characters, the 

 others being common littoral forms. These gravels and sands were 

 proved, by well-sections and other exposures, especially by borings 

 and trenches made by the author and Mr. T. J. Smith, of Hull, to 

 overlie the Boulder- clay. 



