340 Proceedings of the Royal Fhysical Society. 



fluxion-structure communicated to the till by the heavy drag 

 of the glaciers over it.^ Here and there were some current- 

 laid seams of sand and gravel ; a bed of reddish laminated 

 clay without stones lay in the south-east corner. 



The upper surface of this till and clay was even but not 

 level, swelling gently up into a low arch near the middle of 

 the new dock, and shelving rapidly seawards towards the 

 outer extremity of the old one, which (the outer part) was 

 consequently founded on piles. The till, its seams of 

 gravel, and the laminated clay, had been cut clean across 

 before the deposit of the shell bed overlying. 



There therefore exists at Silloth that unconformity between 

 the glacial deposits and the post-glacial which seems to 

 characterise their relations throughout the south of Scotland.^ 

 The Shell-bed. — The shells that gave to this thin bed its 

 character had lived and died undisturbed where they lay. 

 The common shells, so far as I observed, were the common 

 oyster — sometimes to be seen sticking, along with large 

 barnacles, to the stones, and often much perforated by Cliona; 

 Pecten opercidaris in various stages of growth ; the common 

 cockle and mussel ; Fusus antiquus, Buccimim tmdatiom, and 

 some specimens of Littorina littorea and Turritella communis. 

 Tapis pullastra was observed with its valves closed. Here 

 and there stood a boulder of Criffel granite or some other 

 stone richly crusted with corallines (JLepralia) and serpulse. 

 One of the largest of these crusted boulders of Criffel granite 

 (about 1^ foot in diameter) rested on the surface of the 

 stoneless laminated clay. The matrix of this shell-bed was 

 for the most part a bluish fetid-looking mud, much mingled 

 with stones. The large jaw of Bos primigcniits had mani- 

 festly, from its dark- staining, lain upon or among it. The 

 general appearance of the bed was pretty conclusively that 

 of a sea-bottom. Its present position is from 10 to 12 feet 

 above ordinary low-water level. It probably marks the 



^ See Fig. 11 of the writer's paper " On Boulder-Glaciation," p. 181 of this 

 volume. 



2 Crosskey and Robertson ; Monograph (Palteontological Society) of the 

 Post-Tertiary Entomostraca ; Prof. James Geikie, Prehistoric Europe, cha}). 

 xvi. 



