OF PAPA STOUR. 



167 



times prismatic. The fluor-spar was least abun- 

 dant. Hence, it appears, that as the fluor-spar 

 formed the central part of the cavity, it had been 

 last deposited, and that the calcedony, which in- 

 closed the others, was the oldest formed. 



On the north side of Houseavoe, the amygdaloid 

 is covered with the sandstone, floating pieces of 

 which it likewise contains, sometimes of the quart- 

 zy kind. The surface of these floating masses 

 was parallel with the surface of the bed of amyg- 

 daloid. At the west side of Kirk-sand, it distinc- 

 tly alternates with the sandstone, and seems in 

 some places to have a slaty structure. It alter- 

 nates with felspar, containing much quartz, at 

 Culliesvoe. At a place called Herdy-gio, the 

 amygdaloid alternates with breccia, and both these 

 beds are covered with a thick bed of compact- 

 felspar, passing to claystone. Two slips occur at 

 this place, which affect equally the amygdaloid 

 and felspar. The amygdaloid is traversed by 

 small veins of haematite, and the neighbouring- 

 rocks are much impregnated with iron. 



GREENSTONE. 



The two component ingredients of this rock, 

 the felspar and hornblende, being often intimate- 

 ly mixed, it is difficult to distinguish them from 

 each other. The beds are of moderate thickness. 

 To the westward of the Kirk-sand, several beds 



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