Prof. T. G. Bonney—Pebbles in the Bunter Beds. 203 
From what locality or localities then have these pebbles been 
derived? A few present some slight resemblances to the rhyolitic 
rocks of the Wrekin district, and to the rather similar rock recently 
discovered near Nuneaton; but I have no hesitation in asserting that 
we cannot refer them to that source. Again, I may with equal 
confidence exclude the telstones in the Ordovician rocks of North 
Wales. To these, so far as I know them, they bear no resemblance. 
They are more like the felstones which occur beneath the well- 
known Cambrian conglomerate in the Bangor-Carnarvon district, 
but still I cannot refer them to these. They certainly are not from 
any rock now visible at Charnwood, neither are they from the lava- 
flows of the Lake District, though one or two of the specimens 
remind us a little of certain intrusive felstones there. Further, in 
these districts tourmaline is all but unknown. The only case that 
has fallen under my own experience—and it is a rather large one— 
is in the intrusive felsite of Mynydd Mawr. But they recall very 
strongly to my memory the felstones so abundant in the Southern 
Uplands, and in parts of the Highlands of Scotland, which I have 
examined, both in the Museum at Edinburgh, through the courtesy 
of Dr. Traquair, and in a few localities in the field. 
I have also submitted a selection from my specimens to Dr. 
Geikie, Director-General of the Geological Survey, who informs me 
that as a whole they have a remarkably close correspondence with 
the Scotch rocks with which he is so familiar; some agreeing best 
with the felstones of the Southern Uplands, others rather resembling 
those occurring as intrusive masses in the Western Highlands. Two 
specimens in which a fluidal structure was well developed espe- 
cially reminded him of pebbles which abound in a great mass of 
conglomerate of Old Red Sandstone age at Uam Vam; and he 
showed me a specimen therefrom which was as nearly as possible 
identical with one of my own. The dark porphyritic rock he did 
not remember to have seen; but as regards the rest, he entirely 
concurred in my view that they were probably of Scotch origin. 
Since the date of my last paper, one by Mr. J. W. Harrison has been 
printed in the Proceedings of the Birmingham Philosophical Society 
(vol. iii. p. 157), in which he combats the view which I had put 
forward as to the derivation of many of the Bunter pebbles from 
Scotland, and prefers to refer them to an axis of ancient rock now 
buried (except in one or two localities) beneath newer deposits in 
Central England. 
The following paragraph is a statement of his arguments (p. 176) : 
« Professor Bonney refers many of the Bunter pebbles to the Torridon 
Sandstone of the West Coast of Scotland on the ground of their 
agreement in microscopical structure. In reply to this I] would urge 
that the test can hardly be considered decisive in any case, but that 
(a) one quartzite very much resembles another; and (0b) that there 
may be a quartzite further south of the same age and structure. The 
distance also is a formidable objection: the pebbles in the Scotch 
‘Old Red’ are very little larger than those in the English ‘New Red,’ 
although after travelling 300 miles, hurried along and knocked 
together by a current running at the rate of at least three miles an 
