156 The Irish Naturalist, [June, 



thickness. What we found may be shown in the form of a 

 section north and south along the beach (fig. i). The newest 



Fig. I. 



s. 



bed is the blue marine clay, which may be well seen in the 

 space lying inside of the crescent-shaped heap of large 

 boulders which forms a conspicuous object on the shore at low 

 water about a quarter of a mile north of Bray Harbour. The 

 clay is extremely fine and tough, and is full of the shell 

 Scrobicularia piperata, a species whose habitat is between tide- 

 marks on mud-flats and in estuaries. In most cases the pairs 

 of valves are still in juxtaposition, and upright, showing that 

 the shells are lying undisturbed in the place where they 

 lived and died. With this .shell was the well-known Tellina 

 balthica, which lives in similar situations ; and a specimen of 

 Littorina litorea, the Common Periwinkle, was also found. 

 We had not brought excavating implements with us, but with 

 the aid of a broken coal- shovel, kindly lent to us by the 

 nearest resident, we found that towards the southern extremity 

 of its area the bed of clay is at least six feet thick. Especially 

 in its lower portion, the clay contains fir-cones and fragments 

 of wood, washed out of the underlying peat. The peat-bed 

 was next examined. Careful excavation round a selected 

 stump, a large one standing almost upright, revealed the fact 

 that it was firmly rooted in the peat ; the spreading branching 

 roots so characteristic of the Scotch Fir could be clearly traced 

 from their junction with the trunk to their interlaced ex- 

 tremities. Although it was evident that various plants had 

 contributed to the formation of this old forest-bed, no other 

 species could be identified in the short time at our disposal. 

 The peat rested abruptly on a couple of feet of coarse grey 

 sand, in which no organic remains were detected. A little 

 further on, the glacial sands and gravels that form the upper 

 part of the fine coast section between Bray and Killiney rose 

 out of the shingle, cemented into a hard conglomerate, as they 

 are at other places in the neighbourhood. Beyond this the 

 strand was occupied by a denuded surface of boulder-clay, 

 burrowed by that pretty shell P ho las ca?idida. 



