RON A. GEOLOGY. 213 



taming a very scanty proportion of arable ground, and 

 being chiefly appropriated to the rearing of black cattle. 

 Four small harbours are found on the west side, one 

 of which, Archasig hirm, offers a convenient refuge 

 for coasting vessels, with a double entrance ; but it is 

 very little known except to the natives and the neighbouring 

 islanders. It is very imperfectly laid down in Mackenzie's 

 chart, nor does it appear to have been surveyed by him- 

 self. For this reason and because it is the only station 

 from which Rona can conveniently be examined, it may be 

 proper to add a few words respecting this anchorage. The 

 entrance is covered by a rocky islet by which the harbour 

 is completely land-locked, so that vessels may ride 

 securely in any wind and weather, as in a mill-pond, 

 and in good holding ground. The passages are both 

 narrow and beset with rocks, but as these are all visible 

 at half tide, it is easy to steer safely through them : the 

 southern one is most free. It is easily known, in running- 

 down the shore, by the mouth of a cave visible on the 

 island before described. When to those advantages it 

 is added that fresh provisions and water may be pro- 

 cured here, I may be suspected of imitating the narratives 

 of the voyagers who have navigated the South seas ; but 

 those who know the country in question will be well aware 

 of the practical value of this remark. 



THERE is so much irregularity in the positions of the 

 gneiss that it is impossible to give any general account 

 of them, nor is any advantage to be gained by detailing 

 the numerous changes they undergo. On the eastern 

 side there will sometimes be found a great sequence of 

 very straight beds dipping uniformly towards the east, 

 while on the western they lie in a contrary direction ; 

 the two meeting in the middle of the island like the 

 roof of a house. In other places the same beds will 

 be found reversed, the eastern beds dipping to the west, 



