30 Praeger — The Estuarine Clays 



through the strata in the Lagan Estuary, hut in the Quaternary Estuarine 

 deposits in other parts of Ireland, and in England and Scotland. At the 

 Alexandra Dock we have first several feet of clay and sand, which hed was still 

 in course of formation when the works were commenced, its upper surface heing 

 a little above low water mark. Below this is a hed of yellow sand, containing 

 many shells, which prohahly corresponds in age with the flint-hearing gravels of 

 the Kinnegar at Holywood and the Curran at Larne. Immediately underlying 

 this is that very distinct deposit, the Estuarine Clay, which at Belfast, Larne, 

 and other points around our coasts, possesses the same peculiar features and 

 yields the same characteristic fossils. Below this is a hed of peat, corresponding 

 with the suhmerged peat which occurs in so many places on the shores of the 

 British Isles. This rests on fine red glacial sand, the same deposit which occurs 

 at Malone and at the Knock ; which rests in turn on very fine tough red clay — 

 re-assorted Boulder Clay. Underlying this is the Boulder Clay proper, with 

 glacially striated pebbles, which, finally, overlies the New Red Sandstone. These 

 last two formations were not exposed at the Dock, but there is no doubt they 

 underlie the red clay, as they do at other points in the immediate vicinity. We 

 have thus an unbroken series of deposits, stretching from the Boulder Clay 

 Period to the present day, and " offering," says Mr. Stewart, "perhaps the best 

 means of filling up the gap in geological history between the close of the Glacial 

 Epoch and the present day." 



So much for the general section. I now come to a more minute description 

 of the deposits, and shall begin with the section which is shown in Figure 1. 

 This is as follows : — 



1. Blackish clay, with sandy layers, of a depth of six to seven feet, the surface 

 between tide marks. Characteristic shells of this deposit are : — My a arenaria, 

 Cardium edule, Tellina Balthica, Mytilus edulis. Mya occurs in beds of 

 thousands, the shells all in the position in which they lived, and generally with 

 the siphonal tube preserved. Cardium is also very abundant. This bed yielded 

 two specimens of Helix nemoralis, no doubt washed into it by surface water ; 

 and unusually large single valves of Liicina borealis were not unfrequent. 



2. Two feet of coarse yellow sand, with abundance of shells, and also thin 

 layers of twigs and hazel nuts. The shells are often much worn, and generally 

 occur as single valves, and the deposit has all the appearance of an old sandy 

 beach. Pecten opercularis, Littorina litorea, Mytilus edulis, occurred here 

 abundantly, and fine specimens of Tapes pullastra, T. decussatus, and Thracia 

 convexa, which two latter species are not now found living in Belfast Lough. 

 Among the rarer forms which were noticed were : — Fissurella Grceca, Trochus 

 magus, Patella vulgata, Fusus antiquus, Murex erinaeeus, Cyprma Furopcea, 

 Anomia patelliformis, Venus lincta, Cyprina Islandica. Six species new to our 

 Estuarine Clays were observed : — Fusus gracilis, Anomia striata, Tapes virgineus, 

 Venus fasciata, V. exoleta, Area tetragona. Several worn valves of Scrobicularia 



piperala were noticed — this shell will be referred to later on — they had probably 

 been washed from the underlying beds. 



