SiGERSON — On the Physical Geography of Ireland. 19 



the waves. "Every storm," writes Captain. Portlock, "breaks up a 

 new portion of it," covered though it he with sand and gravel, where 

 not denuded. The presence of such a bog, which must have been formed 

 free and above the waves, proves that the land here has sunk. As it 

 contains leaves, nuts, rotten wood, and the elytra of beetles, it is plain 

 that both animal and vegetable life abounded where now nothing 

 is heard but the roar of falling billows. 



Evidence of elevation is seen in the calcareous clays, containing 

 marine shells, which have been found at heights varying from one 

 hundred to four hundred and fifty feet above the sea. One curious in- 

 stance is the bowl-shaped hollow, north of Portrush, explored by Mr. 

 James Smith ; it is ten feet only above sea-level, and contains a large 

 quantity of sand mixed with various marine shells. "This shelly 

 deposit," writes Mr. Smith, " seems to have been a sheltered bay, into 

 which the shells have drifted, with a small admixture of land shells 

 washed down by floods." In the letters descriptive of Magilligan, 

 which its rector, the Eev. Robert Innes, published in 1725, the peculiar 

 physical appearance of the locality was noted. Although he wrongly 

 cited the Deluge as the cause of what he described, his description is 

 accurate and valuable. The evidence of upheaval was recognised by 

 him. " That this land," he wrote, "was formerly sea, I think there 

 is sufficient reason to believe ; for along, at the foot of the mountain and 

 all the coast, is the old bank to be seen, to which the sea hath 

 formerly flowed, at the foot of which everywhere there is sea-sand and 

 shells to be dug up." "The lowland of Magilligan," he adds, "is 

 divided into ridges, or, as we call them, dryms [properly druim] of sand, 

 from one hundred to five hundred yards broad, highest in the middle 

 and sloping on each side to marshy ground, which we call misks, com- 

 monly as broad as the dryms ; the dryms are generally from six to 

 twelve feet higher than the misks, but on the north side (next the 

 ocean) the dryms and misks are narrower, and some of the dryms thirty 

 or forty feet higher than the misks. Both the dryms and misks are 

 parallel almost." The cause of these (the result of the action of sea 

 and winds and of seismical elevation) he considered to be the Deluge. 

 He notes that, owing to water-action as then going on, land had lost 

 a hundred yards within a man's memory. And he reports an interest- 

 ing local tradition, saying, " if we can make anything of Irish fables, 

 the flats of Lough Foyle, which extend in some places a full league, 

 have been formerly part of this land." 



If the "eruption" of Lough Eoyle, recorded in the annals, were 

 an irruption of the sea, much, if not all, of its present basin may have 

 been dry land. It would seem necessary that the river Eoyle should 

 have followed its present direction ; but, in fact, that need not have 

 been. The valley of Pennyburn, which crosses the isthmus of Innish- 

 owen, a little to the north of Derry, and which Captain Portlock accu- 

 rately reports as "exhibiting a channel so natural and well-defined 

 that it is impossible to resist the feeling of being in (the bed of) a river 

 or strait" — this valley I proved to have been a water-passage in recent 



