Natural History of the Island of Rathlin. 39 
stone is overlaid by the basalt. To the east of Bruce’s Castle, the limestone disap- 
pears ; and at Doon Point, which is situated exactly opposite to Fair Head, that singu- 
larly beautiful arrangement of basaltic pillars, which is very imperfectly delineated in 
the sketch, may be observed. 
Sandstone, coals, iron, ore, &c. the substances which form the eastern side of Bally- 
eastle-bay, and which appear different from the common mineral productions of the 
country, may also be traced directly opposite, running under Rathlin, which, in con- 
nection with other circumstances, would tend materially to confirm the opinion of their 
being a continuation of the same general strata. 
Doctor Hamilton entertained the idea, that this island, standing as it were in the 
midst between this and the Scottish coast, may be the surviving fragment of a large 
tract of country, which at some period of time has been buried in the deep, and may 
have formerly united Staffa and the Giant’s Causeway. 
I have already mentioned, that the limestone traverses the island from west to east. 
It is stated, that this chalk or white limestone, when crossed by a basaltic dyke, often 
undergoes a remarkable alteration near the point of contact, the limestone becoming 
granular marble, highly phosphorescent when subjected to heat. On the west side of 
Church bay, within a distance of 100 feet, the chalk is thus intersected by three 
basaltic dykes, and converted in each instance into granular marble. Doctor Hamilton 
supposes, from the sandy texture of this marble, called by him phosphorescent cal- 
careous sandstone, that it might be considered to have been originally formed of water- 
worn grains cemented together ; but the gradual change of the white limestone into 
this substance, together with the fact of marine exuvie being sometimes contained in 
it, seems to preclude this opinion, and renders it more probable that some local cir- 
cumstances may have converted the original limestone into this state. 
“This sandstone,” Doctor Hamilton remarks, “occurs near Larne, and in Island 
Magee ; but in point of phosphorescent qualities, that found in Raghery is much su- 
perior.” 
I was some time ago favoured by Mrs. Mant, of Down and Connor House, with 
some specimens of minerals and fossils, which were collected in Rathlin by the late 
Rey. Andrew O’Beirne, while curate of the island. In consequence of no catalogue 
having been furnished with these, it is uncertain whether they are indigenous to the 
island, or procured from boulders that may have been washed across from the oppo- 
site shore. They all appeared, however, to be similar to those found on the Antrim 
shore, containing some beautiful specimens of the zeolite family, with calcareous spar, 
hornblende, &c. 
My friend, Mr. M‘Adam, M.G.S. examined the fossils, which seemed all to belong 
to the lias formation : the only species he could at the time determine, were the lima 
antiquata and the avicula inequivalvis ; a number of obscure terebratule could also be 
