A LIST OF THE 



Fossils of the Estuarine Clays of the Counties of 

 Down and A ntrim. 



By SAMUEL ALEX. STEWART, 



Fellow of the Botanical Society of Edinburgh, Hon. Assoc, of the 

 Belfast Nat. Hist, and Phil. Soc. 



The term, Estuarine Clay, is intended to signify those deposits, mostly of 

 clay, which have been accumulated in our existing bays and estuaries since 

 the close of the Glacial Period. They are the latest of the long series of 

 geological deposits, and resting, as they most commonly do, on the 

 Boulder Clay, they unite the present to the past. 



The Estuarine Clay often presents beds of considerable thickness, which 

 have been continuously laid down, and are tenanted by the shells of 

 species that have lived and died on the spot. It is to be regretted that these 

 beds have not received more attention, as they offer perhaps the best means 

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

 Era and the present. 



These Estuarine Clays are widely spread in Britain, being of consider- 

 able thickness, and covering areas of some extent in such important 

 estuaries as those of the Clyde and of the Mersey. In the North of 

 Ireland we have several of these beds. That at Belfast exceeds twenty 

 feet in thickness, and is spread over an area of at least four or five square 

 miles. It may be seen at Belfast, Sydenham, Holywood, Bangor, and 

 Kilroot. Similar, though apparently less extensive Post-Pliocene accumu- 

 lations, are to be found on the shores of the Loughs of Larne and Strang- 

 ford, and also at Lough Foyle, and near Coleraine. Of the two latter no 

 detailed account has been published, and I have had no opportunity of 



