IS FIN GAL'S CAVE ARTIFICIAL? 233 



circle is completely closed for 315 by land, distant at farthest from five 

 to seven miles. From Dutchman's Cap, bearing nearly due west, to 

 the " Stac " off Iona, there is comparatively deep water of forty to fifty 

 fathoms. The charts, however, show that rocks approach the surface. 

 " Five-Fathom Rock," " Dangerous Overfalls," and soundings of less 

 than ten fathoms, push half-way across the Passage of Tiree. Mac- 

 kenzie's Rock, which dries in four feet, guards the other entrance, 

 and no Atlantic surge could pass into Loch Tuadh or the Sound of 

 Iona, without changing its direction twice and almost at right angles. 

 But Donegal receives the impetus of the tremendous billows which 

 break against the steep cliffs of Mizen Head, or rush up the narrow 

 gorges with which the exposed coast of the Northern Hebrides is so 

 deeply scored. Staffa is singularly sheltered. It makes it antece- 

 dently extremely improbable that this particular spot would be selected 

 by the ocean as a place on which to " prove its strength." Words- 

 worth was both a landsman and a poet, and, as he says 



" In a motley crowd, each the other's blight, 

 Hurried and hurrying " 



only saw it. His language, however, has undoubtedly been made a 

 vehicle of scientific error. 



" Caves worn by the sea are due to the set of the currents, the 

 force of the breakers, and the grinding of the shingle, which inevitably 

 discover the weak places in the cliff, and leave caves as one of the re- 

 sults of their work, modified in each case by the local conditions of the 

 rock " (" Encyclopaedia Britannica "). Assuming that this is a com- 

 plete statement of the law of marine erosion, how was Fingal's Cave 

 " hollowed out of columnar basalt," and therefore rightly classed by 

 Professor Boyd Dawkins, " among caves worn by the sea " ? There is 

 no current setting into this bay. The spring tides rise llf feet, neaps 

 8 feet, and range 4^- feet. The maelstrom of that part of the ocean 

 is " where Corryvrechan's surges driven " make " the caldron of the 

 spectral sea," but to the south, behind Colonsay. The force of the 

 breakers is inconsiderable. Either they are the result of local disturb- 

 ance formed to the east of Tiree, or the ground-swell and heaving of 

 the sea after a storm. The island is fully protected by its own fore- 

 shore. The perpendicular columns suggest an " unknown profundity 

 of depth." But the basalt on the west is over 50 feet above the sea- 

 level. A spit of conglomerated trap or tufa prolongs under water a 

 flat, rocky shore. There is a succession of rocks and shoals. The 20- 

 fathom line is a mile distant, the 10-fathom half a mile, immediately 

 followed by rocks, and 12, 15, and 9 feet of water. As the cave is in the 

 southern face, it appears to be impossible, in the present state of the 

 coast, that a wave with any momentum could strike directly upon that 

 end of the island. As MacCulloch sat on one of the columns, though 

 the long swell raised the water at intervals to his feet, the movement 

 was silent, and the surface of the sea apparently undisturbed. There is 



