1873.] BRYCE JURASSIC ROCKS OP SKYE AND RAASAY. 331 



These sheets of trap are continuous across the high moors to the 

 southwards with the trap of the central or Storr range, at the base 

 of which beds of lignite are contained in the trap (see Map). 



The road from the lake to Steinchol crosses this riclge ; on reach- 

 ing the bridge by the parish church and mill, and for some distance on 

 both sides, up and down the burn, dark shales are interstratified with 

 . black basalt, and altered to the state of Lydian stone ; they overlie 

 and underlie the basalt, and are entangled in it in a most confusing 

 way. The level of the stream at the bridge is not less than 60 ft. 

 above sea-level; hence to the sea the stream runs on trap ;*and the bed 

 must therefore be part of that which appears in the cliff at the S.E. 

 side of Loch Staffm, under which the shale beds of the tideway 

 pass. 



This shale bed is the only one left of the whole series ; and the 

 overlying trap is divided from the doleritie sheet below by this thin 

 shale bed only. The strata had here been denuded before the over- 

 lying trap was poured forth ; the shale bed may thus have been en- 

 tangled between the two traps, if contemporaneous ; or if the doleri- 

 tie were the earlier, we have the altered shale already prepared as 

 the floor of the overlying trap. The trap cliff on the west (i. e. at 

 S.E. angle of the bay) and the fossiliferous beds on the E. come 

 together at the same level, at a depression where a paved road, the 

 only passage from the shore, ascends to the top of the cliffs. The 

 trap rock at the bridge and church is part of this great intrusive and 

 depressed body of overlying trap, which can be traced continuously 

 from the church till it ends in the cliffs. The explanation of these 

 curious relations probably is, that, as the level tract at the head of 

 the bay is occupied by Oxford clay, the lowest beds of the overlying 

 trap invaded the strata on the east side at the first irruption of the 

 fluid rock (see range of beds and map). 



At about one mile west of the hotel, in the bed of a stream above 

 the bridge, where the Uig and Duntulm roads diverge, the Oxford 

 clay is seen in its normal state of a dark adhesive clay. Thence it 

 stretches westwards by the base of the Quiraing mountain, and mani- 

 fests its existence in many places, though not actually visible, by 

 the tossed and broken surface, and the slips and subsidences on 

 the new public road lately made, in the construction and conser- 

 vation of which the engineer has found the greatest difficulties 

 from this cause. The grand scenery of the Quiraing, with its sub- 

 sided plateau and wondrous surrounding pinnacles, is a slip from 

 the mountain-precipice, with all the parts in upright positions, owing 

 to the lateral thrust exerted on the Oxford-clay beds, partly by the 

 enormous weight of rock over them, but partly also, no doubt, by 

 the hydrostatic pressure of columns of water which could obtain no 

 passage through the clay beds. 



The Uig Beds. 



These beds consist of adhesive clay, dark shales, and arenaceous 

 limestone. The nature of the ground is such that the beds are well 

 seen only at the west angle of the bay, near the headland. There can 



