Core—The Rhyolites of the County of Antrim ; with a Note on Bauaite. 109 
remember that the proportion of alumina present does not vary greatly through 
the whole igneous series; and the lithoidal rhyolites of the Tardree area, with 
their uniform, soft, clayey decomposition-products, seem especially calculated to 
give rise to the pale varieties of bauxitic clay in the county of Antrim. I may 
add that the decomposing rhyolite of Scolboa yields a considerable proportion 
of its alumina after mere boiling with sulphuric acid, showing that products 
soluble in this acid have already arisen within it. Neither the original alkali- 
felspars nor kaolin would give such a result. A similar but less marked reaction 
is obtainable from the altered rhyolite of Templepatrick. 
V.—EsLERSTOWN. 
This is the ‘“ Esterstown,” and “ Esterston” of the Survey Memoir to Sheet 
20 (pp. 10 and 11), and lies two miles north-east of Kells and Connor. I must 
confess that I have not personally visited this exposure. Its apparent area has 
been much reduced on the latest issues of the geological map, the northern two- 
thirds of it beng now represented as Upper Basalts; and Mr. M‘Henry informs 
me that the pisolitic iron ore which les below these basalts can here be seen 
coming in above the rhyolite. Meanwhile the ‘actual contact with the surrounding 
rocks cannot be seen,” * a statement that hardly justifies the section immediately 
following it upon p. 11 of the Memoir. Here the rhyolite is represented as a 
magnificent dome, against which the basalts and iron-ore abut. It was probably 
this section that caused Sir A. Geikiet to remark that one of the Antrim 
rhyolites, south-east of Ballymena, appeared to cross into the Upper Basalts. 
Similar features are shown in the longitudinal section, sheet 31, with the 
addition of a dyke of basalt, cutting the rhyolite at a point to which no 
surveyor is likely to have had access. The rhyolite is described as “a 
disintegrated porphry,” similar to the main type at Tardree; and it may fairly 
occur as a local intrusive neck or laccolite. But its relations to the Lower Basalts 
are confessedly not proven, and there is no reason to regard it as so important a 
mass as is Shown upon the published sections. 
VI.—KirkInRI0LA. 
The exposure of rhyolite is here very obscure, and was originally noticed by 
Mr. W. J. Knowles of Ballymena.{ It occurs round about the ancient churchyard 
of Kirkinriola, on the slope of Berk Hill, and the rock has been at some time laid 
* Mem. to Sheet 20, p. 10. 
} Op. cit., Trans. Roy. Soc., Edin., vol. xxxy., p. 171. 
{ Mem. to Sheet 20, Geol. Surv. Ireland, p. 10. 
TRANS. ROY. DUB. SOC., N.S. VOL. VI., PART IU. R 
