34 
Praeger — The Estuarine Clays 
interesting specimen which I found here consisted of a large valve of Cyprtna 
Islandica, to the interior face of which a full-sized Oyster was adhering, its 
shell fashioned to the shape of the Cyprina , and the other valve was lying 
close at hand. This tells of a slow rate of accumulation of the deposit. The 
Cyprina lived and died, and the valves of its shell in time broke asunder. Then 
the Oyster came and settled in the untenanted house of its predecessor, and it 
grew and flourished before the slow rain of fine mud buried both m a quiet 
grave. Pholas crisp at a and P. Candida occur frequently; and a single 
specimen of Pholas dactylus , new to our Estuarine Clays, was observed. At 
the base of the bed, where it is quite sandy, there is abundance of Cardtum edule 
—this stratum evidently corresponds with the lower clay of the first section. 
Below this we come directly upon the red sand ; there is no trace of the peat 
bed. The sand is nearly twenty feet in thickness, and rests on the red clay. . 
It is interesting to compare the sections above described with other sections 
in the Lagan Estuary which have been examined by local geologists. 
The beds exposed when Spencer Basin was in course of construction, on the 
opposite side of the river, which were so thoroughly examined by Mr. Stewart, 
consisted simply of some twenty feet of Estuarine Clay, which he divides mto 
three well-defined zones : — 
1. Surface clays ; abounding in littoral species. 
2. Zone of Thracia convexa ; characterised by shells which live in five 
to ten fathoms of water. 
3. Scrohicularia zone ; in which littoral species again predominate. 
The physical and palaeontological differences between the two latter were 
more marked than at Alexandra Dock ; the beds of peat and sand were not 
exposed. 
Borings at King Street, in the centre of the town, under the superintendence 
of Mr. fm. Swanston, F.G.S., showed a depth of no less than twenty-eight feet 
of Estuarine Clay, at the base of which was a layer containing many twigs and 
hazel nuts. Next came twenty-four feet of fine running sand, which yielded on 
examination four species of Eoraminifera, two of these being the two forms 
obtained in the red sand at the Dock. Beneath this was fifty feet of very fine 
red Boulder Clay, in which two Foraminifera were found to occur very 
sparingly, namely Rot alia Beccarii, and Polystomella striato -punctata , the 
same species which formed the only fossils of the red sand in the Dock sections. 
The fine clay rested on Boulder Clay, as it usually occurs in our neighbourhood, 
100 feet in thickness, and abounding in Foraminifera, underlying which were 
the sandstones of the New Red. 
At Sydenham Railway Station a different state of things may he noticed. 
We have only a couple of feet of Estuarine Clay, replete with the shells of 
species which live between tide-marks, its upper surface being about three feet 
above high-water mark, or sixteen feet higher than the top of the Estuarine 
Clay at the Dock. Then comes a foot of yellow sand, at the base of which is 
a narrow zone crowded with the crumbling remains of littoral species. This 
