Cote—The Rhyolites of the County of Antrim; with a Note on Baurite. 11h 
1873, the rhyolite having been mistaken for Carboniferous sandstone. Berger 
had correctly appreciated the rock sixty years before; he observed that it adhered 
slightly to the tongue, that it contained smoky quartz, lamellar felspar, and brown 
mica, and that its specific gravity was 2°43. My own specimens, however, give 
2°50; the rock, while less crystalline than that of Tardree, has its gravity increased 
by the abundance of ferromagnesian material. 
The geological surveyors* noted the occurrence of a vertical flow-structure, 
which can be distinctly seen in the quarry. ‘The rock is of a cool grey colour ; 
it is not scoriaceous, but is somewhat powdery and trachytic in texture. 
Under the microscope, its groundmass resembles that of the rhyolite of Temple- 
patrick churchyard ; but biotite is unusually abundant. Cumulites are well seen 
in the glass, and minute felspathic prisms of the Templepatrick type, many of 
them simply twinned, occur freely, imparting a granular effect here and there 
between crossed nicols. Porphyritic crystals are scarce, but biotite occurs among 
them. One of the quartz grains has been restored to something of its former 
outlines by the growth of a broad micropegmatitic zone around it, m which quartz 
finally predominated. 
In the Survey Memoir, the dark mineral is regarded as probably hornblende ; 
but the description given of its microscopic characters (p. 22), and examination 
of the rock itself, would lead to a different conclusion. 
The vertical position of the flow-planes at Ballycloughan is certainly a good 
piece of evidence for regarding the rhyolite as occupying a volcanic neck. 
Mr. G. H. Kinahanf has affirmed that the rhyolites of this area are intrusive in 
the basalts, and has placed them as contemporaneous with the rock of Temple- 
patrick. Sir A. Geikie ¢ has stated that they occur as ‘intrusive bosses, sheets, or 
veins.” I suspect that any lava-flows which may have been poured out from these 
centres were worn away during the long interval when the Lower Basalts were 
being denuded—an interval that was marked by the production of iron-ores, 
bauxites, and ferruginous clays in Co. Antrim. The rhyolitic conglomerates of 
Ballypalady and Glenarm occur characteristically on this horizon. 
VIII.—Criovucuwaer. 
We now reach the most northerly, and perhaps the most remarkable exposure 
of lithoidal rhyolite. Between Cloughwater School and the main road from 
Ballymena to Cushendall, near the spot marked ‘‘ Meeting Ho.” on the Ordnance 
map, there lies a little hollow of bogland, draining northward into the Clough 
River. Looking south, against the semicircle of dark basalt hills, with the hue 
*Mem. to Shect 20, pp. 11 and 22, } ‘‘ Manual of Geol. of Ireland,” p. 162. 
t Op. cit., Trans. Roy. Soc., Edin., vol. xxxy., p. 171. 
