Prof. Cole cO T. Hallissy — Tlie Wexford Gravels. 505 



pressure of ice moving from the north-east. On weathering, the 

 chocolate marl shows a distinct lamination. 



In spite of occasional loamy bands in the gravels and of gravelly 

 patches in the boulder-clays, we have no doubt that Hull's main 

 contention ' is correct, and that Wexford, like other parts of Eastern 

 Ireland, records (1) an invasion of foreign ice from the north and 

 north-east, (2) an epoch of recession, which allowed of the formation 

 of shelly gravels as a residual concentrate from the englacial moraine 

 (boulder- clay) which was left behind by the shrinking ice, and (3) 

 a second boulder-clay, in which local rocks are conspicuous, and 

 which represents a return of colder conditions and an. extension of 

 the Irish ice. 



We agree with Kinahan and Wyley ^ that the flints found in the 

 Wexford drifts were derived from a region of chalk which once 

 stretched across the Irish Sea and the English Channel. Kecent 

 work ^ clearly sliows how much Cretaceous material has been lost 

 during the formation of the North Atlantic and its eastern inlets. 

 The beach east of Kilmore contains numerous large and almost 

 unrolled flints, which probably come from chalk that still remains in 

 the floor of the adjacent sea. They are larger and fresher on their 

 surfaces than tliose found in the chocolate clay. The coal that is so 

 abundant in this clay near Wexford town is no doubt derived from 

 the waste of Carboniferous strata, while the lignite, which is found 

 also at Kill of the Grange in Co. Dublin,'' may represent a widely 

 spread Cainozoic stratum, and is of too frequent occurrence to be 

 attributed to the beds of Co. Antrim. 



The Pliocene shells, on which A. Bell has laid such stress, are no 

 doubt also derivative. The Pliocene sea, of which the St. Erth Beds 

 are a record, is held to have formed the plane surface of northern 

 Cornwall/ which clearly corresponds with that of South-East Ireland. 

 The finding of iron- stained shells in the drift of Co. Carlow has been 

 cited ^ as fair evidence of the existence of Pliocene deposits in Ireland, 

 which have been concealed by the boulder-clays, or which have been 

 worked up later into them. 



There can be little doubt that the shells of the Wexford gravels 

 have all been derived by concentration from the chocolate boulder- 

 clay that was deposited from the Irish Sea ice. The same is true of 

 the stony materials that form the gravels. Any of these materials 

 may in turn have found its way into the later boulder-clay which 

 overlies both the gravels and the chocolate clay ; but this later 

 boulder-clay is far richer in subangular blocks of local origin. 



^ Pln/s. Gcol. Ireland, 1878, p. 84. 



- Mem. to Sheets 169, etc., 1879, p. 13. 



^ G. A. J. Cole & T. Crook, " Rock-specimens dredged from the Floor of the 

 Atlantic" (Mem. Geol. Surv. Ireland), 1910. A. Jukes-Browne, Building of 

 the British Isles, 1911, fig. 53. 



■* W. J. Sollas & R. LI. Praeger, "Notes on Glacial Deposits in Ireland. 

 II. Kill o' the Grange " : Irish Naturahst, 1895, p. 321. 



® H. Dewey, Proc. Geol. Assoc, vol. xxv, p. 173, 1914. 



^ G. A. J. Cole, "The Problem of the Liffey Valley": Proc. Roy. Irish 

 Acad., vol. XXX, sect. B, p. 11, 1912. 



