566 [Proc. B.N.F.C. 



20th March. 



MISS S. M. THOMPSON.—" ON THE SUPPOSED 

 OCCURRENCE OF A PATCH OF WHITE LIAS 

 OR RHAETIC ROCK ON THE SHORE N. OF 

 MACEDON POINT, BELFAST LOUGH." 



In the spring storms of some five years ago, a patch of grey 

 rock, unlike any other rock occurring on the shore, was exposed 

 about a hundred yards to the north of Macedon Point, which 

 had previously been completely concealed by a deep covering 

 of sand and shingle. Its unfamiliarity attracted my attention 

 and I subsequently showed it to Professor Cole when visiting 

 at Macedon, and he at once pointed out its resemblance to the 

 so-called " oolite " found at Waterloo near Larne. The patch 

 of rock occurs close to the sea-wall of Macedon, and lies between 

 two of the basaltic dykes which occur so abundantly on this 

 shore ; the sedimentary rock is seamed and interlaced with 

 intrusive veins of the basalt which have hardened and altered 

 it. I have placed some specimens of the Macedon rock upon 

 the table as well as some from Waterloo, when the great 

 similarity in appearance will be immediately noticed ; also some 

 specimens with basaltic veins which interestingly demonstrate 

 the probability that these enclosing dykes have preserved the 

 patch from denudation by the sea, which covers it completely 

 at high tide. The length of the patch is about 60 yards. 



I subsequently submitted some specimens of the rock to Mr. 

 M'Henry of the Geological Survey of Ireland, who replied as 

 follows : — 



" I have received your specimen. Certainly it looks to me 

 " exactly similar to the Waterloo Rhaetic rock. It is very 

 "interesting to get representatives of the Rhaetic beds at 

 " Macedon, and if this be so it is doubtful indeed if the new 

 " Red Sandstone Rocks there belong to the Bunter division ! 

 '' I have made a note of this on our 6 inch map and shall draw 

 " Sir Archibald Geikie's attention to the fact when next he 

 " comes to Ireland." 



