234 



THE POPULAR SCIENCE MONTHLY. 



T-. -S8^.^^^^^BB^.* 



Fig. 2. West Side of Staffa, 14G3. G. W. W. Showing Arched Entrance to Cormorant's Cava;. 



no shingle. The prismatic blocks are refractory. If a wave struck 

 with sufficient force to dislodge the drums, or if, undermining the tuff, 

 it strewed the beach with hexagonal or pentagonal blocks, these smooth 

 stones, with polished sides, buried in the finer material, would offer 

 very great resistance to any further waste of the cliff. Although a 

 channel of 18 feet at mean low water approaches and enters the cave, 

 there is no ledge over which the material could have been carried. 

 The sharp conchoidal fracture would not serve the purpose of such 

 crystalline rocks as quartz or granite, and furnish the fluid wave with 

 a serrated edere. 



The cave is not formed in what would naturally be considered the 

 cliff ; least of all in its weakest place. After examining the Admiralty 

 Chart, " the reader will, no doubt, pass with pleasure to the rich de- 

 scription by Dr. MacCulloch." That author, however, says that the 

 whole of Fingal's Cave seemed like a ship heaving in a sea-way, and 

 therefore his survey may be considered less trustworthy than that of 

 Commanders Bedford and Creyke (Admiralty Chart, 1857). It seems in- 

 correct to say, " The caves are so numerous that they may be said to per- 

 forate at brief intervals the whole face of the island ; but those which 



