at the New Alexandra Dock, Belfast. 33 



reached in the deepest excavation at the Dock— the foundation of the Rudder 

 Well, over fifty feet below high water mark— although fifteen feet of it had 

 then been passed through. No organic remains were discovered here, but this 

 was probably due to the small sample submitted for examination. 



As regards the microscopic fossils of these beds, it may be remarked that of 

 the 104 species of Foraminifera recorded from the Post-tertiary deposits of the 

 North-east of Ireland, by Mr. Joseph "Wright,* the Alexandra Dock sections yielded 

 forty species, their distribution being as follows : — Estuarine Clay, 40 ; sandy 

 layer overlying peat, 4 ; grey sand under peat, 5 ; red sand, 2. Of twenty 

 species of Ostracoda, all occurred in the blue clay— one in the sandy layer above- 

 mentioned, two in the grey sand, and two in the red sand. One species of each 

 of these orders was found in every deposit throughout— Rotali a Beccarii and 

 Loxoconcha guttata. 



If we now turn to the section at the outer entrance of the Dock, some 600 

 feet north of the one just described, some striking differences will be noticed. 

 At the west side of the entrance basin the Estuarine Clay is only four feet 

 thick, and below it is one foot of yellowish clay, which represents the bed of 

 peat. This rests directly upon the fine red sand, the surface of which is here 

 twelve feet higher than at the upper end of the works. At the east side, while 

 making excavations for the inlet culvert, an interesting section was exposed (see 

 Figure 2). Beneath some feet of clay and sand was a bed of coarse blackish 

 sand, with abundance of shells, at the base of which were some two or three 

 inches of almost pure shells. In this layer Littorina litorea was in great 

 abundance, along with Cardium edule, Mytilus edulis, Lucinopsis undata, and 

 Thracia convexa — some littoral and some deep-water forms, it will be noted. 

 This mixture of species is curious, but I think there can be little doubt that the 

 five to twenty fathom shells which occur here in profusion were washed out of 

 the upper clay. The faunas of the two beds (the sand and upper clay) are 

 remarkably similar, considering the very different conditions under which they 

 must have been laid down ; but a closer examination showed me that the deep- 

 water species in the yellow sand were almost confined to its lowest zone, which 

 abounds in the species that especially characterise the upper division of the 

 Estuarine Clay, which lies immediately below it. A fine valve of the rare 

 Cardium Norveyicum occurred here, several examples of Utriculus obtusus, and 

 a single specimen of U. mammillatus, which is new to the Clays. Immediately 

 below the shell layer is the Estuarine Clay, which at this point is only two feet 

 thick. The deposit is very sandy, except at its upper surface, and is replete 

 with species which have lived and died in what was then the sandy bottom of a 

 bay several fathoms deep. Full-sized examples of the large Lutraria elliptica 

 are of constant occurrence, along with large specimens of My a truncata, and 

 Thracia convexa, Solen vagina, and Tapes pullastra ; of these Mya and Tapes 

 are the only species now found living in the waters of our Lough. A rare and 



•Wright— "Post-tertiary Foraminifera of the North-east of Ireland."— Proc.Belfast 

 Naturalists' Field Club, Vol. I., Appendix V. 



