Professor Geikie on Geology of St Abb’s Read. 193 
a muck wider area than they now occupy. This is evident from the 
appearance at the surface of the intrusive porphyrites near St Abb’s 
Head. These, there can be little doubt, cooled and consolidated 
under the surface — the tuff which formerly covered them has been 
washed away. The intrusion of these porphyrites marks the closing 
stage in the volcanic activity of Old Red Sandstone times. It was 
not until after lavas and fragmental materials had ceased to be 
erupted, and the throat of the old volcano had become plugged with 
angular debris and blocks, that the rocks in question were injected. 
They evidently cooled under some pressure, but were probably not 
of very deep-seated origin. Whether they ever rose to the actual 
surface of the old volcano and overflowed, we cannot tell, for the 
whole of that surface has of course disappeared. It is obvious, 
however, that the molten masses from which they came must have 
been of essentially the same composition as that from which the 
bedded porphyrites were derived. 
V. Glacial Phenomena. 
The district described in this paper has been entirely overflowed 
by ice. This is proved by the generally glaciated contour of the 
rocks, which are smoothed from IST.W. to S.E. The escarpments 
of porphyrites that faced the ice-flow have been bevelled off, and, 
notwithstanding the weathered character of the rocks, well-marked 
striae are met with here and there, the trend of which is E. 35 S. 
Glaciated stones and clay occur in patches in the hollows of the 
headland, and a considerable mass of till occupies the hollow that 
separates the headland from the Silurian uplands. This is w r ell 
exposed in section at Pettico Wick. It presents no features that 
require to be noted here, but is made up of the debris of rocks 
which have come from the west or north-west. 
PRIVATE BUSINESS. 
A ballot was taken, and the following gentlemen were duly 
elected Fellows of the Society : — Mr Alexander Goodman More, 
Alexander M. M‘Aldowie, M.D., Mr James Hunter, Mr William 
Gilmour, Mr Herbert H. Ashdown, M.B., and Mr J. Mackay 
Bernard. 
VOL. XIV. 7/10/87 N 
