1858.] MTIRCHISON NORTHEEN HIGHLANDS, ETC. 411 



the east hill above Kkkwall, and may be best paralleled with some of 

 the rocks near Wick, — being hard, tough, and thick-bedded enough to 

 be used as rude building-stones. They are also bituminous, and are 

 here and there copiously charged with iish-remains ; for in them we 

 found Coccosteus and many remains of other ichthyoHtes. 



These stony bands are followed, on the north side of the harbour, 

 by thin flagstones, which, in addition to numerous ichthyolites, are 

 laden with the little Crustacean Esiheria (p. 404), which, wherever it 

 occurs, is equally characteristic as the fishes, being abundant in some 

 spots of Caithness, particularly near Thurso. With the exception of 

 the partial axis of the lower sandstone of Kirkwall, and a lower con- 

 glomerate near Stromness, which is formed out of and rests upon 

 granite, just like the examples on the coast-confines of Caithness and 

 Sutherland, the whole of Pomona seems to be so occupied by the 

 ichthyolitic flagstones, that if the Roman leader who named the island 

 had been a naturalist, he might aptly have named it Piscina. Occu- 

 pying all the interior hills as well as the plains on which the famous 

 Stennis Stones stand, these flagstones are admirably exposed on the 

 shore to the JST.E. of Stromness, where dipping away from low bosses 

 of granite and the conglomerate formed out of that rock, they form 

 broad undulations, all along the northern shore, the cliffs between 

 Breakness and Holbrow rising here and there to 150 feet or more 

 above the sea. 



It is unnecessary here to recapitulate the numerous ichthyolites 

 which Pomona has yielded. We ourselves met with Osteol&pis, Coc- 

 costeus, Asterolepis, Dipterus, Diplopterus, Diplacanihus, and many 

 fossil plants. The works of Agassiz and Miller teem with data on 

 this head, — Dr. Traill having supphed the former with many of the 

 new specimens*. 



In availing myself of the opportunity to visit the northernmost 

 of the Orkney Islands (Eonaldsha) and the Shetland Isles, in the 

 steamer of the Commissioners of the Northern Lighthouses, I was 

 prevented from extending the observations made in the environs of 

 Kirkwall and Stromness, into the adjacent island of Hoy. Of the 

 general order, however, in that island, there can be no doubt ; for, 

 whether it be viewed from Dunnet Head, from the sea, or when 

 sailing under its cliffs on the east, west, and north sides, or by 

 walking along the opposite shores of Pomona, near Stromness, or 

 again when standing, as we did, upon the low, small island of 

 Gremsa, the succession is unmistakeably exhibited. Observed in all 

 these ways, the flagstone-rocks of Caithness, occupying low cliffs and 

 terraces, are seen clearly to pass under and to be superposed by the 

 reddish and yellowish sandstone of the HiU of Hoy, which, where it 

 extends to the vertical maritime precipice on its north-eastern face, 

 with its outlier the Old Man, has been ascertained to have a height 

 of 1130 feet. I much regret not having explored this headland, 



* The finest collection in Pomona is in the possession of the Rev. C. Clouston. 

 (See Dr. Maloolmson's memoir, p. 348.) The traveller will find, in the excellent 

 and comfortable inn at Stromness, kept by Capt. Flett, a little museum containing 

 many of these ichthyolites. 



