270 A. J. Jukes- Browne—Foraminiferal Limestones. 
the pass between it and Moel Tryfaen. That it came, in part at least, 
over Moel Smythaw is evidenced, I think, by the great erratic of 
felsite mentioned above; but our main guide must be the immense 
boulders of probably Welsh rocks which occur in the sands, together 
with the still more curious fact of the foreign pebbles in the drift 
overlooking the Bettws Garmon valley. Both these things point to 
a commingling of the two moving masses—the Irish Sea glacier and 
the Welsh Bettws Garmon glacier. They would meet nearly at right 
angles. This, from the analogy of rivers, we should expect to 
produce a kind of back-wash, the front of the Bettws Garmon glacier, 
and the side of the great glacier, would be squeezed out together into 
the angle between the two. The pressure thus produced would raise 
this isolated mass of ice to a higher level than either, and force it 
into a place of rest on the east side of Moel Tryfaen. Here it would 
ultimately melt, and the contained debris would wash down the 
slopes where now we see them. In this way the great local boulders 
have been carried all round Moel Smythaw in more than a semi- 
circle, and a similar course has been followed by the small foreign 
stones on the side of Bettws Garmon. In this way also any rie- 
beckite rock found on Moel Tryfaen may have come round from 
Mynydd Mawr. 
There are, however, to the north of this spot several other valleys, 
as Nant Francon and Llanberis, which should have produced ana- 
logous results. Doubtless they did so, but when we examine the 
area where the back-wash of these should lie, we find it is open 
country, where they would not be allowed to rest. It is only in the 
case of Moel T'ryfaen that there is a nice little quiet corner, where 
they could be undisturbed if once they were introduced, and this 
fully accounts for their being so exceptional. 
VIII.—ForamtnirerAL LIimesToNES FROM THE GRENADINE ISLANDS, 
West Inpizs. 
By A. J. Juxzs-Browne, B.A., F.G.S. 
HE specimens which form the subject of this note were sent to 
me by Mr. G. F. Franks, F.G.8., of Bridgetown, Barbados, 
and were obtained by a correspondent of his from the island of 
Canouan, one of the Grenadine group. Mr. Franks had made slides 
from three of the samples, and having recognised them as foramini- 
feral limestones he sent them to me for fuller examination, stating 
at the same time that the limestone was associated with a compact 
igneous rock, apparently a porphyritic andesite, with abundant 
glassy ground mass enclosing streams of microliths. He also sent 
fragments of four different varieties of the limestone, and my friend 
Mr. W. Hill has been kind enough to cut mea slide from one of 
these which appeared different from the others. 
Two of the specimens are of a light but dull red colour, hard, 
crystalline and traversed by thin veins of calcite. Slides cut from 
these two and examined with a one-inch objective showed them to 
have practically the same structure. They consist of a calcified 
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