168 SCAKPA, TARANSA. GEOLOGY. 



SCARPA, TARANSA, SCALPA. 



THESE three are the only detached islands of con- 

 siderable size connected with Harris : in a geological 

 view they may be considered as portions of it. The 

 substances found in the two latter render them worthy 

 of notice, although they present too little variety to call 

 for a detailed consideration. 



Scarpa and Taransa are each mountainous, the former 

 consisting of one rocky mountain of gneiss about 1000 

 feet in height, and the latter, of two hills of less eleva- 

 tion connected by a sandy isthmus. I discovered nothing 

 in Scarpa worthy of particular regard, but the granite 

 veins of Taransa are conspicuous for the magnitude and 

 beauty of the crystals of mica which they contain. The 

 smaller are generally very regular, and are crystallized 

 in short prisms or tables, often two inches in their 

 long dimension : the larger are less regular, attaining to 

 nearly a foot in length. They are rarely found so large 

 in Scotland. 



Scalpa, or Glas island, situated on the eastern coast, 

 is conspicuous for its light-house, being low, and, like 

 all the rest of this shore, formed of irregular pro- 

 tuberances of gneiss. To the geologist it is remark- 

 able for a bed of serpentine, which the works required 

 for the light-house have so far laid bare as to render 

 it of very easy access throughout the whole of its con- 

 nections. It traverses the promontory on which the 

 light is erected, being, like the gneiss in which it lies, 

 very irregular in disposition, but generally placed 

 at a high angle, often indeed in a vertical position. At 

 its boundary it in some places passes into a schistose 

 rock, not easily distinguished at first sight from clay 

 slate, and consisting of a smooth mixture of talcose 

 schist with hornblende. In other places the boundary 



