422 RAMBLES OF A GEOLOGIST. 



CHAPTER XII. 



THE Orkneys, like the mainland of Scotland, exhibit their 

 higher hills and precipices on their western coasts : the Ward 

 Hill of Hoy attains to an elevation of sixteen hundred feet ; 

 and there are some of the precipices which skirt the island 

 of which it forms so conspicuous a feature, that rise sheer 

 over the breakers from eight hundred to a thousand. Un- 

 like, however, the arrangement on the mainland, it is the 

 newer rocks that attain to the higher elevations : the heights 

 of Hoy are composed of that arenaceous upper member of 

 the Lower Old Red Sandstone, the last formed of the Pa- 

 laeozoic deposits of Orkney, which overlies the ichthyolitic 

 flagstones and shales of Caithness at Dunnet Head, and the 

 ichthyolitic nodular beds of Inverness, Ross, and Cromarty, 

 at Culloden, Tarbet Ness, within the Northern Sutor, and 

 along the bleak ridge of the Maolbuie. It is simply a tall 

 upper storey of the formation, erected along the western line 

 of coast in the Orkneys, which the eastern line wholly wants. 

 Its screen of hills forms a noble background to the prospect 

 which opens on the traveller as he ascends the eminence be- 

 yond the Free Church manse of Frith and Stennis. A large 

 lake, bare and treeless, like all the other lakes and lochs of 

 Orkney, but picturesque of outline, and divided into an up- 

 per and lower sheet of water by two low, long promontories, 



