134 OVERLYING AND TRAP ROCKb. 



spondences remaining perfect. Of this, a very beau-, 

 tiful example occurs in the valley of Coruisk, in Sky. 

 If minute and numerous fragments of the including 

 strata are often enclosed at the immediate contact, or 

 in the walls of the vein, while also limited to these, 

 the same circumstance occurs in the larger masses, 

 but with variations attended by peculiar interest. In 

 this case, the fragments are often partially fused, and 

 thus far converted into the substance of the invading 

 rock ; the larger mass having effected that change to 

 which the smaller was inadequate. The schistose 

 rocks thus often present a further very instructive 

 appearance ; the laminae being separated, and their 

 intervals filled by air bubbles ; so that the thickness 

 of the entangled portion is increased, exactly as it is 

 by heating it in an ordinary fire. The plates of 

 that work on the Western Isles contain many 

 drawings illustrative of these, as of other facts de- 

 scribed in the present book ; and I may here refer to 

 what I cannot reprint. 



More minute details, however interesting, would 

 extend this chapter to an unwieldy length. Yet I 

 must remark,, that although I have here preferred do- 

 mestic examples, because I desire that every one may be 

 ableto examine my evidences, the same phenomenahave 

 at length been observed in other parts of Europe, by 

 those who can now discover what they have been taught to 

 see and understand. The last appearance quoted, which 

 so few have chosen or have been able to see, even when 

 placed before them, has been now confirmed at Plauen 

 in Saxony ; the shale of the red marl has been found 

 converted into siliceous schist at Blaua Kuppe in the 

 same country, as the magnesian limestone has into 

 chert, in the Vicentin, and as others have been found 

 crystallized into white marble in the Pyrenees. It is 

 satisfactory to find that there are persons who will be 



