D. Balsillk — Limestone Fragments, "Hock and Spind/e." 201 



(12) Adams, F. D., " The Nepheline Syenite of Dungannon, Ontario " : Amer. 



Jour. Sci., 1894. 



(13) Holland, Sir Thomas, in Mem. Geol. Surv. India, vol. xxx, 1901. 



EXPLANATION OF PLATES XI AND XII. 

 Plate XL 

 Fig. 1. Nepheline-syenite [ x 120] showing general structure. M. melanite 

 garnet ; N. nepheline ; B. asgirine ; A. apatite ; Ca. calcite. 

 ,, 2. Kadial apatite [ x 150]. 



Plate XII. 

 ,, 3. [x90.] Graphic intergrowth of mica and calcite — radial apatite in 



upper portion. 

 ,, 4. [ x 90.] Graphic intergrowth of calcite with olivine and magnetite. 



II. — Note on the Limestone Fragments in the Agglomerate ok 



the " Rock and Spindle " Volcanic Yent, St. Andrews, Fife. 



By David Balslllie, St. Andrews. 



IN the agglomerate of the volcanic necks of Eastern Fifeshire are 

 incorporated, as has long been known, numerous fragments of 

 sedimentary rock. These, it is generally believed, represent the 

 broken-up remains of the strata which at some former time occupied 

 their sites. Many of them have obviously been subjected to 

 excessively high temperatures, others show no sign whatever of 

 igneous action. Thus, occasionally we find quartzites and lydian stone 

 representing what once must have been sandstones and clay shale; 

 or, again, the constituent layers of a sandy or carbonaceous shale may 

 be seen to be still adherent and so little altered as to display on 

 a freshly exposed surface admirably preserved plant-remains. Lime- 

 stone blocks also occur sometimes converted into marble, frequently 

 unchanged; in the latter case, exhibiting on their weathered exteriors 

 the remains of those organisms which give at once the clue to the 

 conditions accompanying the deposition of their parent stratum. It 

 is with special reference to these limestone fragments that this note 

 has been written and particularly to those occurring in one vent — the 

 well-known "Rock and Spindle" — a mile and a half to the east of 

 St. Andrews. 



To be quite brief, the " Rock and Spindle " volcanic vent can now 

 be seen to penetrate a portion of that group of Lower Carboniferous 

 sediments which in Central Scotland is known as the Calciferous 

 Sandstones. Intercalated among the strata through which it has 

 risen is one well-known limestone band, the Encrinite-bed. Numerous 

 fragments of this calcareous stratum are, of course, to be found in the 

 agglomerate just as we should expect. In addition to these, however — 

 and the fact does not seem to have been formerly emphasized — are 

 frequent pieces of a white limestone which in the immediate neigh- 

 bourhood has no counterpart. From these last-mentioned fragments 

 I have at one time or another obtained the following fossils. Most of 

 them were collected in the north-western portion of the vent, and 

 especially did they occur in the decomposed blocks above high- 

 water mark. 



