lo Lamplugh : Estiiarine Shells at Sand-le-Mere. 



level on the shore as the estuarine muds. Still farther south- 

 ward, as the southern margin of the basin was approached, 

 the estuarine deposits re-appeared, presenting nearly the same 

 succession in reverse order as that seen on the northern margin. 



The dip of the estuarine beds on both sides toward the 

 middle of the hollow suggested at first sight that they passed 

 beneath the peat and fresh-water mud which lay between them, 

 and therefore probably also beneath the larger mass of peat 

 exposed at low tide. But I was unable to convince myself 

 that this was actually the case. The presence of detached 

 cakes and rolled lumps of peat in the estuarine deposits at 

 both margins proved, at any rate, that there was peat in the 

 basin before the estuarine muds were deposited ; therefore if 

 the peat-bed which I saw exposed were of later age, it would 

 be necessary to suppose that the detached pieces were derived 

 from some older mass buried out of sight. On the whole, I 

 think it most likely that the estuarine beds enwrapped and 

 covered the peat, since this is the usual order of the sequence 

 in the Humber basin,* and I fovmd nothing actually to disprove 

 it in this case. 



The mollusca had evidently lived where their shells occurred. 

 Most of the bivalves had their valves united, and many were 

 in the position of life. The cockles, which were the most 

 abundant, were unworn and well-preserved though all com- 

 paratively small and thin-shelled. The mussels, also rather 

 small and thin, lay in sparse clusters, and were mostly crushed. 

 Tellina and Scrohicularia were much rarer, but were well- 

 grown. The little univalve Hydrobia occurred in myriads, 

 giving a speckled or streaky aspect to some of the layers ; 

 at the northern end of the exposure it was also present, in 

 association with the peaty roots and stems of a grassy plant, 

 in a higher band than the other shells. 



The deposit and its fauna clearly indicate a quiet estuarine 

 creek regularly invaded by the salt-water tide with sea-level 

 approximately the same as at present. The peat and the fresh- 

 water mud are evidence of a stage, probably earlier, when the 

 hollow was beyond reach of the tide, either because of a higher 

 level of the land or the existence of a protective barrier. 



* Cf. C. Reid ' The Geology of Holderness,' Chapter viii., pp. 77-93, 

 W. H. Crofts ' Notes on the Post-Glacial Deposits of Hull and District,' 

 Trans. Hull Geol. Soc, Vol. IV., 1899, p. 36 ; also ' Notes on the Alexandra 

 Dock Extension, Hull,' ibid. Vol. V., 1901, pp. 57-62. 



Naturalist, 



