I874-75-] l °7 



Post-Glacial sea formed the deposit of sand beneath the peat. Then 

 it retreated, leaving a swamp in which the peat grew. Afterwards 

 the land sank, the sea returned, swept away most of the peat, and 

 buried the remainder under a bed of gravel. Similar beds of peat 

 have been found beneath the sea-beach in many places on the east 

 coast of Down and near Portrush. The secretary of this Club and 

 I were present at the disinterment of the skeleton of an Irish elk, 

 which was found in a deposit of shell-marl, about half way between 

 Newtovvnards and Donaghadee. The shell-marl was covered with a 

 layer of peat, which was again overlaid by a deposit of gravel beneath 

 the vegetable soil. The shells (mainly Limn sea) had accumulated in 

 apool ofwater, in which the elk had probably been drowned. Intime 

 the pool became silted up, and formed a suitable soil for the growth 

 of peat. The peat had been in its turn covered by the sea, which 

 buried whatever portion it did not succeed in removing, beneath a 

 bed of shingle. 



(3.) After the lapse of a probably lengthened period, during which 

 the peat was deposited, the land again sank, but not to so low a level 

 as during the Post-Glacial period. 



The peat which had grown during the previous elevation was now 

 mainly swept away, leaving occasional patches in hollow places, as 

 in the cases to which I have just referred. The inland seas that 

 now covered all the ground at a low level were of a tranquil cha- 

 racter. The more compact portio?is of the stratified sands andgravels, 

 deposited during the previous submersion, were now able to resist the 

 denuding action of the calm waters with which they were surrounded, 

 the looser portions being at the same time swept away. There would 

 thus be a second series of islands in these seas, the higher group 

 consisting of the glacial mounds that had resisted denudation during 

 the previous submersion ; the lower group — the ridges of sand and 

 gravel which had not been swept away during the second submersion. 



(4.) The land ?vse once ?nore, and ultimately attained its prese?it 

 level. The mounds and ridges that appeared as islands during sub- 

 mersion were now hills, some of them co?nposed of unstratified glacial 

 drift — the rubbish deposited by ancient glaciers and icebergs ; others 



