82 Cote—The Rhyolites of the County of Antrim ; with a Note on Baumite. 
now exposed exactly in the form shown in Mr. M‘Henry’s section; but the rude 
columnar jointing of the rhyolite certainly supports his argument. It might fairly 
be urged, however, that the rhyolite flowed against a gravel bank, which was 
subsequently invaded by the basalt. The bold basaltic dykes in the quarry might 
tempt one, indeed, to regard the basalt on the north face as similarly intrusive ; 
on the other band, its delicate amygdaloidal character points to its being a portion 
of a lava-flow. I cannot agree with Mr. M‘Henry that ‘the most important 
point in the evidence” is to be found at the eastern end of the north face; two 
rival interpretations there seem possible. 
By the kindness of Dr. H. Woodward, F.R.S., editor of the ‘ Geological 
Magazine,” I am enabled to reproduce Mr. M‘Henry’s excellent figure of the 
western section (fig. 1), which requires more attention than he himself has drawn 
to it. In the field, it was necessary to prepare a clean surface of the rocks, and to 
clear away a certain amount of débris, before the whole of Mr, M‘Henry’s details 
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SERS 
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Fie. 1. 
Section at west end of Templepatrick Quarry. Drawn by A. M‘Henry, m.n.1.a. 
B—Basalt. C—Chalk. G—Flint-Gravel. T—Rhyolite. 
Superficial deposits occupy the top of the section. 
could be verified. The rhyolite certainly lies between two layers of the old flint- 
gravel, which are fairly continuous, while a long tongue of decomposed rhyolite 
runs upwards on the right, closely mingled with fragments of basalt and with the 
characteristic reddened flints. The features along this plane are those of a fault- 
breccia rather than of a thin intrusive sheet; and a long crack traversing the 
rhyolite farther down, in continuation of the plane of the breccia, is filled with 
dark clay, and also suggests a surface of movement. The occurrence here of an 
inclined fault, with a downthrow to the west, would account, moreover, for the 
form of the basalt patch above the rhyolite, which now exhibits a triangular 
exposure on the quarry-face, the apex pointing downwards. The left side of this 
inverted triangle is formed by the original junction of the base of the basalt and 
the dint-gravel over which it flowed; while the right-hand side is formed by the 
