8 . ■ Hull — Raised Beach of Cantyre. 



fissures ; but it is impossible to observe a fissure in tliese tougb 

 scb.istose rocks of the old sea beach of such dimensions as the above 

 (about 150 feet in length, and 35 or 40 in depth) without being 

 impressed with the conviction that the time required for this work 

 must have been long indeed. 



The caves which are found at intervals all round the coast, and 

 which form a range of natural rock-hewn compartments at a level 

 of 10 to 30 feet above the present tidal limits, are perhaps the most 

 convincing of all the various evidences of ancient sea-action which 

 can be adduced. These caves are hewn, not only in the softer 

 strata of the Old Eed Sandstone, but also in rocks of such firmness 

 as the porphyries of Davar Island, at the entrance to Campbelton 

 Bay. This island, which on the landward side slopes gradually down 

 to the water's edge, on the opposite side is girt by a wall of rugged 

 rock, rising vertically from a ledge which slopes gradually down- 

 ward and terminates in a vertical cliff under low water. The wall 

 above the ledge is honeycombed with fissures and caves in a position 

 beyond the reach of the sea, and unquestionably referable to a past 

 age. One of these caves has a double mouth, and is stated by 

 Professor Nicol to be 130 feet in length, and was originally even 

 longer, because the face of the cliff is itself being gradually worn 

 backwards, as is attested by the blocks of rock which lie scattered 

 over the surface of the sloping ledge, which are loosened by the past 

 rains and spray, and carried off by the waves. Professor Nicol 

 remarks upon the length of time which must have been necessary to 

 excavate such a cave as this. He says : "Even though some fissure 

 in rock, or softer vein of stone, may have determined the greater 

 waste in this place, still the time required for its formation must 

 have been enormous. It seems, indeed, almost impossible to estimate 

 the number of ages spent by the waves in cutting ovxt a cave of 

 130 feet in length in rocks of such hardness as tte porphyries of 

 Davaf Island."^ 



Caves in the rock -bound coast between Campbelton and Keill are 

 of frequent occurrence. The Old Eed Conglomerate in which they 

 are for the most part excavated is, in itself, well calculated to 

 astonish any one who, like myself, sees it for the first time. It is 

 a "piidding- stone," in which the plums are often of the size of the 

 largest mortar shells, reaching three feet in diameter. Yet are they 

 always so smooth and rounded, that they must have been rolled 

 about for a long time by the waves before they became imbedded. 

 Tbe stones and boulders consist of felspar and claystone porphyries 

 (some like those of Davar Island) indurated grits and sandstones, 

 white and coloured quartz, and more rarely granite, but (as Pro- 

 fessor Nicol has observed) there are no specimens of the prevailing 

 rock of the country — mica-schist. I could not, however, help re- 

 marking frequent examples of that peculiar "liver-coloured" quartzite 

 which occurs so abundantly in the New Eed Conglomerate of Cen- 

 tral England, and the source of which is still so mysterious. 



Some of the caves at Keill, close by the spot where St. Columba 

 1 Geology of Cantyre, p. 422. 



