74 A DESCRIPTION OF THE [Ch. V. 



the gneiss, but also the limestone, and other beds contained 

 therein ; and, in traversing the serpentine of Scalpa, already 

 noticed, they consist of the usual mixture of felspar and 

 quartz, with talc superadded, thus partaking of the composition 

 of the magnesian rock through which they pass. 



Such are the leading features of the primary schists of the 

 Western Isles of Scotland; and to these might be added a 

 description of the chlorite-schist, clay-slate, and quartz-rock, 

 which compose the more southern islands ; but, by so doing, 

 the details would far surpass the limits of this work, in con- 

 sequence of the complicated and undefined nature of these 

 rocks, owing to the present imperfect state of geological 

 nomenclature. Dr. M'Culloch has indeed given a copious 

 and circumstantial account of these islands, and his work 

 ought to be very carefully studied by all who are desirous of 

 obtaining a knowledge of the primary rocks. 



In the northern part of Europe the crystalline rocks appear 

 to abound over very extensive tracts, and although the climate 

 and the impracticable nature of the country oppose great ob- 

 stacles to their minute investigation, yet they have been 

 carefully examined by several distinguished geologists. 



For the present, however, Von Buch's descriptions of the 

 rocks of Norway and Lapland must suffice ; and as far as the 

 limits of this work will admit, it is proposed to give an outline 

 of his observations, which bear on the subject now under 

 consideration. 



Von Buch observes that the Swedish and some other 

 foreign mineralogists have described granite as of frequent 

 occurrence ; but that he has ascertained that this rock is a 

 great rarity in Sweden, as well as in the whole of the north. 

 This is in accordance with the experience of Haussmann, who 

 has affirmed that granite, such as occurs in Saxony, Silesia, 

 the Hartz, and in Lower Austria, was never seen by him in 

 Sweden. The rock thus mistaken for granite is, says 

 Von Buch, a clear and decided gneiss ; it is distinctly slaty, 

 and its mica lies in scales one above another, and never in 



