VOL. LXXX.] PHILOSOPHICAL TRANSACTIONS. 64 1 



siliceous gravelly concrete ; below which are horizontal beds of indurated marl, 

 of various thicknesses, from 6 to 12 inches. The whole of these beds, taken 

 together, are about 4 yards. Lastly, are 10 yards of rude lava, containing 

 specks of quartz and mica unaltered, pieces apparently of granite, and some 

 nodules of calcined chert. The whole is incumbent on regular basalt pillars, of 

 various dimensions, from 18 to 6 inches diameter, varying in the number of 

 their sides, some having 5, some 6, and others 7 sides. They are also as 

 variously disposed ; those on the western extremity of the glen being straight, 

 and lying horizontally ; while of those on the east side some are bare, and stand- 

 ing perpendicularly ; and others, which are surmounted by the rude lava, are 

 inclined and curved, as if they had taken that form in cooling from the pressure 

 of the incumbent weight. See Tab. fig. 14, pi. 6. Many of the pillars are 

 very full of bladder-holes ; the articulations of the joints are close, though not 

 so close as those of the Giant's Causeway ; but, like those, their tops, where 

 exposed, are either concave or convex. 



At the extremity of the glen is an insulated rock, supported by basalt pillars 

 (fig. 15,) which are somewhat curved and inclined. Incumbent on these are 

 other pillars, lying nearly horizontal, and having a rude face of lava to the 

 westward. At high-water this rock is inaccessible without a boat ; but at low • 

 water it may be easily got at, by stepping from one tumbler to another ; and on 

 the north side it is not difficult to climb to the top. The bottom of the glen is 

 covered with large tumblers of lava the whole way down to the rock, and pre- 

 sents the rudest scene imaginable. Opposite Ardlun Head, on the north side of 

 Loch Leven, is Ben Vawruch, a high promontory, with strata in horizontal 

 beds ; and the hill being of a circular figure gives it the appearance of having 

 several terraces, with a kind of castle or cairn on the top. The columnar pillars 

 at Ardlun are more or less regular for an extent of near a mile and a half; and 

 all the projecting points of Loch Leven, as far as the eye could reach, appeared 

 to be composed of lava. 



Landed without difficulty on the eastern side of StafFa. The greatest extent 

 of the island is about 1 mile from n. e. to s. w. and in one part not more than a 

 quarter of a mile from s. e. to n. w. It is tolerably level, the shore every where 

 steep, and the cliffs formed by basalt pillars or rude lava. On the south side, 

 rising from a nearly horizontal bed of reddish stone, are beautiful basalt pillars 

 of considerable height, and standing vertically ; at a little distance are others in- 

 clined, and others which are curved, very similar to the ribs of a ship. There 

 are 3 caverns amidst the basaltic pillars ; one of them is now usually called Fin- 

 gal's Cave ; but the school-master at Icolmkill said that the Erse name for it is 

 Fein, which signifies the melodious or echoing cave. On the northern part of 

 the island, and at the cove where they landed, the cliffs are of coarse lava, 



VOL. XVI. 4 N 



