336 Proceedings of the Royal Physical Society. 



Holland, on tlie western shore, the yellow sandstones are 

 thrown against the flags by a fault which is admirably seen. 

 The sandstones dip to the north of west, and, on following 

 the coast line southwards, they graduate downwards into the 

 grey flags. 



In the south side of the island, at Housbay, and in the bay 

 west of Lamb Head, the flagstones roll over to the south-east, and 

 a similar passage upwards into the yellow sandstones may be 

 noted. The small area occupied by this series at Lamb Head 

 is bounded on the north side by a fault. 



A small patch of yellow sandstone, which is quarried for 

 building purposes, occurs between Odin Ness and Burgh 

 Head, but as it is bounded by faults, its relation to the flag- 

 stones is not apparent. 



The greater portion of the island of Shapinshay is likewise 

 occupied by the Flagstone series. The sections exposed on the 

 coast line prove, beyond all doubt, that the same beds are 

 constantly repeated by gentle undulations. Along the west- 

 ern shore, between Stromberry ISTess and the Gait, the general 

 dip is to the north-north-west, but as the observer traverses 

 the shore of Veantro Bay and the coast line between Balfour 

 Castle and How, he cannot fail to note the frequent changes 

 of dip which bring the same beds to the surface again and 

 again. In the south-eastern corner of the island, however, 

 there is a small patch of red and yeUow sandstones inter- 

 stratified with grey flags. Though the gradual passage be- 

 tween the two groups, which is so clear in the northern islands, 

 cannot be made out in Shapinshay, there can be little doubt, 

 from the character of the strata, that the patch of sandstones, 

 between Haco's Ness and Kirkton, are near the base of the 

 arenaceous series. A small fault separates the two groups 

 to the south of Kirkton, which obscures the relations 

 between them, and it is highly probable that this dislocation 

 may be the northern prolongation of the great fault to be 

 described presently, on the Mainland. This conjecture is 

 ^rengthened by the fact that, though the flagstones on Sha- 

 pinshay roll about in every direction, yet the preponderance 

 of dips is towards the south-east, and this is especially the 

 case on the eastern shore of the island. Bearing this in mind 



