1856.] NICOL — QUARTZITES, ETC. OF N.W. SCOTLAND. 39 



land, Dot yet raised out of the ocean. At this time, too, has taken 

 place the transport of those innumerable "perched stones" which 

 we have noticed throughout all this region, apparently floated away 

 on icebergs from the mountains on the east, and deposited on the 

 tops of the lower hills as they again rose above the waters to their 

 present elevation. 



It is an important fact in connexion with all these great and 

 repeated changes of level, that this district is remarkably free, for 

 Scotland, of igneous rocks. No large masses of any of them are 

 seen at the surface, and even veins are by no means common. The 

 granite- veins at Cape Wrath, and near Lochs Inchard and Laxfiord, 

 are the most important exceptions ; and then the porphyries and 

 serpentines of Assynt, Loch Broom, and Loch Greinord. Trap- 

 veins occur rarely in Assynt, but seem scarce known on the main- 

 land, either to the north or to the south. This is the more remark- 

 able when we consider the proximity of Skye, where these rocks, 

 of many different ages, are so fully developed ; or contrast this part 

 of Scotland with the west coast of Argyll, where they break out 

 almost every hundred yards. 



It thus appears that this portion of Scotland has formed a peculiar 

 isolated region, even from an early period. Perhaps a still more 

 important lesson to the geologist may be found in the fact, that 

 changes so singular in character, and so immense in extent, have 

 taken place in this country, and yet almost no trace of the powerful 

 agent by which they were effected appears on the surface. 



