CHAP. XI.VII 
THE RHYOLITES OF ANTRIM 
427 
cated with the surface is quite conceivable, hut what we now see appears 
in every case to be a subterranean and not a superficial part of the protrusion. 
Most of the rhyolitic exposures are extremely limited in area — mere 
little knobs, sometimes rising in the middle of a bog, and never forming 
conspicuous features in the landscape. The relation of these rocks to the 
basalts are generally concealed, but the isolation of the small rhyolitic 
patches leaves no doubt that they are intrusive as regards the surrounding 
Fig. 370. — Intrusive rhyolite in the Lower Basalt group of Antrim, Templepatrick. 
] 1, Chalk ; 2 2, Gravel ; 3 3, Bedded liasalt ; 4 4, Rhyolite, intrusive. 
basalts. This relation is well seen at Templepatrick, where it was first 
observed by Mr. M'Henry of the Geological Survey (Fig. 370). The rhyolite 
there forms a sill which has been thrust between the basalts and the gravel 
that underlies them, the basalts being bent back and underlain by the 
acid rock. 1 
The largest and most interesting of the Antrim rhyolite tracts covers a 
space of about ten square miles in the heart of the basalt-plateau to the 
north-east of the town of Antrim. It rises to about 1000 feet above the sea, 
and forms a few featureless hills, some of which are capped with basalt. 
The best known localities in this tract are Tardree and Carnearny. The 
rock is chiefly a somewhat coarse-textured lithoidal rhyolite, but includes 
also vitreous portions. 
Fig. 371. — Section across the southern slope of Carnearny Hill, Antrim. 
a a a, bedded basalts ; 5, rhyolite. 
Owing to the cover of soil and turf, the junction of this mass with the 
surrounding basalts cannot be so clearly seen as in the sections of the Inner 
dykes and bosses. Hor have any satisfactory traces been found of vesicular or pumiceous bands 
such as might mark the upper surfaces of true lava-streams. Professor Cole has described what 
he calls “The Volcanoe of Tardree” (Geol. May. July 1895). If the Tardree mass ever was a 
volcano, which is far from improbable, its superficial ejections have long ago disappeared. At 
least, after the most dOigent search, I have been unable to discover any trace of them, all that 
now remains appearing to me to be the neck or core of protruded material. 
1 The progress of quarrying operations during the last eight years has somewhat destroyed 
the section as exposed in 1888. But we now see that the basalt has not only been bent back 
but is underlain by the acid rock. 
