Yol. 52.] AT BaRRI, GLAMORGANSHIRE. 477 



Above Below 

 Ordnance- Ordnance- 



Quay-level, coping round Dock, Basin and Deep Lock 



High-water ordinary spring tides 



High-water ordinary neap tides 



Mean sea-level at Barry 



Low-water ordinary neap tides 



Low-water ordinary spring tides 



Bottom of Dock 



datum. 



datum. 



feet. 



feet. 



26-50 





19-70 





11-30 





1-60 







8-3 





164 





200 



1. The blown sand occurs only on the eastern side of the tidal area, 



whence it was evidently drifted by the south-west winds. The 

 supply was never great, and is now of course entirely cut off. 



2. The Scrobicularia-cl&y occurs in considerable force towards the 



north-eastern end of the excavation. It is a stiff, brownish 

 clay, jointing vertically as it dries. It contains an abundance 

 of Scrobicularia plana, with the valves united, and in this 

 and other respects resembles the mud which is now being 

 deposited in the more sheltered parts of the Bristol Channel. 

 In the present case it found no rest on the shoals east of the 

 island, but accumulated in some force from near Warren Tump 

 upwards along the river- valley, as indicated on the map. 

 The greatest thickness seen in the dock was 9 feet. 



3. This sand and shingle forms the base of the Scrobicularia-cla.y, 



into which it passes insensibly upward. It ranges from 2 to 

 8 feet in thickness, according to local circumstances, and is full 

 everywhere of recent shore-shells, all more or less rolled. 

 Among these the following species have been identified by 

 Mr. Clement Reid: — Scrobicularia plana, Tellina balthica (the 

 thin-shelled estuarine form), Cardium edule, Patella vulgata, 

 Littorina liltorea, L. rudis, and L. obtusata. 



Southward this sandy and gravelly tidal wash extends in a 

 patchy manner among the rocky shoals towards the present foreshore, 

 where it is still in course of formation. The deposits described 

 above were all in process of being laid down, until the area was 

 taken in hand by the Barry Dock Company in 1884. They rest 

 upon a conspicuously eroded surface of the strata about to be 

 described, with which also they contrast strongly in their contents 

 and character. The erosion is attributable to the scour of the tide 

 when the sea first gained access to the estuary round the eastern 

 end of the island. 



The series of deposits upon the description of which we now enter 

 forms a continuous sequence from top to bottom. It may gene- 

 rally be described as a mass of fine clayey silt with abundant remains 

 of sedges in the position of growth throughout, and with four or 

 more bands of peat, only three of which, however, are of any 

 importance. For convenience of reference I have numbered the 

 beds all through, but the clays or silts which fall under the figures 



4. 6, and 8 are practically identical. The greatest thickness seen 

 amounted to about 35 feet. 



