THE GEOLOGY OF BERMUDA. 13 



trasts strongly with the high dips observable in the drift-rock on the 

 Main Island in the vicinity of Hamilton, ^car the south end of Ire- 

 laud Island I observed a stratum of almost perfectly unconsolidated 

 sand abounding in shells. In the lower layers of this sand the shells are 

 of marine species. In the uppermost layer the shells are those of land 

 snails. The stratum is overlain by ordinary drift-rock. The layers 

 containing marine shells attain an elevation of about 15 feet above the 

 water. In spite of the lack of consolidation of this stratum, I can hardly 

 doubt that its lower layers are truly a beach formation, and that the 

 transition from marine to terrestrial fossils marks an epoch of elevation. 

 A conglomerate evidently of beach origin appears at Stock's Point, 

 the part which remains in situ on the north shore of the Point reaching 

 an elevation of about 12 feet; though Mr. J. T. Bartram, an enthusiastic 

 self-taught naturalist residing near the spot, assured me that, in a part 

 of the bluff which has been removed in quarrying, the conglomerate 

 attained a considerably greater altitude. Unquestionable beach-rock 

 appears on the north shore of St. George's near Fort Catherine. The 

 rock is at that locality richly fossiliferous. But the most instructive 

 localities of the beach-rock which I have observed are along the south 

 shore of the Main Island. At various points along that shore the 

 beach-rock, more or less fossiliferous, with its characteristic gentle dip 

 seaward, forms a gently sloping platform, at the back of which rises a 

 low cliff of drift-rock with steep landward dips. The most thoroughly 

 satisfactory locality which I observed for the exhibition of the relations 

 of the two rocks is near Devonshire Bay. There the beach-rock, which 

 forms (as in other localities along the south shore) a platform gently 

 sloping seaward, is in places fine-grained and very hard, in other places 

 fossiliferous with shells and pieces of coral of considerable size. It is 

 surmounted by the usual low cliff of drift-rock with high landward dips. 

 Overlying the hard beach-rock of the shore platform, and underlying 

 the drift-rock of the cliff, is a stratum of unconsolidated sand, resem- 

 bling that observed at Ireland Island, containing marine shells in its 

 lower layers and land shells in its uppermost layer. This stratum of 

 sand is mentioned by Nelson,* though he seems to have misapprehended 

 the character and relations of the fossiliferous beach-rock which under- 

 lies the sand stratum. The sand stratum is not recognizable at some 

 of the localities on the south shore where the phenomena are in other 

 respects as above described. 



* Op. cit., p. 107. 



