18 S. V. Wood, Jun. — Sequence of Glacial Beds. 



Wexford and those occurring in the basin of the Severn, and 

 between both of these and the Middle Glacial of the East of England, 

 may be well founded, I venture no further opinion than that the 

 fauna of the Severn gravels differs materially from that of the East 

 Anglian fomiation,^ and that these gravels have not yet been 

 described as overlain hj Boulder-clay. 



No mention, either, is made by him of Tellina ohltqua among the 

 Wexford shells; nor is that shell among those given from the 

 Severn gravels. He is also silent as to Tellina calcarea {proxima or 

 lata) being among the Wexford fossils — a shell never absent from 

 any of the Glacial series, or even from what I venture to think may 

 be among the oldest of the Post-glacial, viz., Moel Tryfaen, though 

 this shell is among those enumerated from the Severn basin. Never- 

 theless, I ought to mention that I have traced the Middle Glacial, 

 from its great expansion in East Anglia along a narrow and tortuous 

 belt across the more central counties, to a part where, around Eugby, 

 it is cut through by valleys whose drainage belongs to that system 

 which falls into the Severn at Tewkesbury. 



With respect, however, to any identity between the Middle Glacial 

 of East Anglia and the gravels of Moel Tryfaen and the Macclesfield 

 neighbourhood, the case seems to me to admit of more positive 

 determination, and that determination to be adverse to such identity. 



To make the case intelligible, I place the beds of the Eastern side 

 of England in that (descending) order which I have for some time, 

 in co-operation with the Eev. J. L. Kome and Mr. F. W. Harmer, 

 been endeavouring to establish.^ 



Newer fa. Ordinary river-gravels and brick-earths without Ci/rena fluminalis — 

 Post-glacial \ a series probably extending over considerable time. 



'b. Hessle (Boulder) clay. 



c. Hessle gravel (Kelsea Hill bed) with Cyrena Jluminalis and the 

 Nar valley beds, 

 uiuer J ^. Gravels mostly occurring on plateaux and on hills ;— sporadic accu- 

 ^ost-giacia mulations of small extent and at all levels, and connected with 



the denudation of the Glacial beds during their emergence from 

 l^ the great depression. 



Here, or more precisely between c and e, intervenes the gi-eat denudation and 

 principal unconformity. 



' e. The purple (Boulder) clay of Yorkshire witJiout \ Both of these 

 •pj. I chalk, passing down into f have inter- 



pPP.®'! < e . The purple (Boulder) clay «f/<7i chalk, and contain- ( calated beds 

 Uiacial. \ .jj^ ^^g Bridlington shell-bed. ; of sand. 



\ e" . The great chalky (Boulder) clay. 

 Middle if. The Middle Glacial sand and gravel, with chalky Boulder-clay in 

 Glacial. ( some, though very rare, instances either in it or at its base. 



A marked unconformity and a considerable denudation of the beds g and h here 

 intervenes. 



' The list of Mr. Maw's Severn Gravel shells, identified by Mr. Jeffreys, contains 

 thirty-five forms of Mollusca, all of them living. Eight of these (inclusive of Tellina 

 Balthica) are unknown to the Crag, and of such eight two only range into the Arctic 

 seas. As to the East Anglian shells, sec post. 



^ For this, see principally the following papers, viz. :— S. V. "Wood, jun. and J. 

 L. Home, Quart. Jouru. Geol. Soc, vol. xxiv. p. 146. S. V. Wood, jun. and F. W. 

 Harmer (Brit. Assoc, 1868), Geol. Mag., Vol. V. p. 452. S. V. ^\''ood, jun., in a 

 paper read before the Geol. Soc. on Dec. 8, 1869. 



Older 



