502 D. Balsillie — The Geology of Kinkell Ness. 



it will be obvious tbat any portion of sucb a mass which by chance 

 had remained clear of xenolithic ingredients would tend to display 

 its characteristic symmetrical jointing, the jointed igneous rock 

 passing insensibly, as observed by Fleming, into the " agglomerate". 



^7%\ 



FlG. 1. — Diagram to illustrate structure of Rock and Spindle shore stack as 

 seen from the east side. TT, older bedded tuffs of the vent forming the 

 beach platform. A, intrusive basalt with included fragments. B, a portion 

 of the basalt— forming the spindle — which, remaining clear of fragments, 

 has jointed symmetrically. C, dyke cutting both A and B. Further 

 references in text. 



In light of what has just been said, Fig. 1 is given as representing 

 the structure of the Rock and Spindle shore stack. The appearance 

 of B as intrusive into A may be due merely to movement of one part 

 of the mass against the other. The opinion is, of course, perfectly 

 admissible that B has been introduced, while A was still uncoole'd 

 and had become welded on to it. There can be no question as to the 

 posteriority of the dyke C which stretches far out into the eastern 

 wall of the opening, and indeed cuts another neck. It appears to 

 belong to the final chapter in the volcanic history at this part. 



The geologist walking over the beach platform of ash at Kinkell 

 will have no difficulty in detecting by their prominence — contingent 

 upon their superior durability — other masses of similar kind to the 

 Rock and Spindle itself. Among these may be mentioned specially 

 the first large stack that meets the eye on coming round Kinkell 

 Ness from St. Andrews. This, at a first inspection, appears to be an 

 exceedingly coarse agglomerate that encloses fragments of the older 

 dark tuff. Careful examination, however, will again, it is believed, 



