414 Submergence. 



pect, with sea-shells, broken and entire, of the following 

 species : * 



LAMELLIBRANCHIATA. 



Cardium echinatum, C. edule * and its variety rus- 

 ticum, Astarte borealis, * A. compressa (var. globosa), 

 A. sulcata, Cyprina Islandica, Tellina Balthica,* 

 My a ? Saxicava rugosa, * mactra ovalis, * and various 

 fragments. 



GASTEROPODA. 



Trochus magus. Lacuna vincta,Littorina littorea,* 

 Turrit&lla communis., * Pleurotoma pyramidalis, 

 P. turricula, Buccinum undatum, Nassa reticulata, 

 Purpura lapillus, * Murex erinaceus, * Trophon 

 antiquum, T. clathratum, T. scalaroides, T. ? Denta- 

 lium, and various fragments. 



The stones on the ground consist of species of diorite, 

 felspar, porphyry, jasper, chalk-flints, Silurian slate, &c. 

 The surface of the sands beneath the boulder-beds is 

 very irregular, and has been much eroded, in my opinion 

 probably by the pressure of a glacier during the depo- 

 sition of the moraine matter that forms the overlying 

 Boulder-clay. The latter contains large masses and 

 smaller fragments of igneous rocks from the Lower 

 Silurian mountains on the east, jasper, quartzite, purple 

 and blue slate, &c., and looks like part of an old moraine. 

 All the way up the slope, from the neighbourhood of 

 Llandwrog, quantities of moraine mounds cumber the 

 ground, and ice-scratched stones abound, and even 

 small water-worn pebbles are marked by glacial striae. 

 Some of the blocks are very large. In the underlying 

 gravels also stones sometimes occur, faintly marked by 



1 Those marked * were also found by Mr. Etheridge and the 

 author, 



