269 
1911-12.] Report on Rock Specimens. 
From these facts it is at once apparent that the stones are not the debris of 
rocks in situ. Moreover, more than half of them (53*42 per cent. ) are either 
ice-moulded or well glaciated, and the proportion of angular and rounded 
fragments to the glaciated ones is not much in excess of what is to be found 
in our “ tills ” or boulder-clays, and very much less than that occurring in 
the moraines of Alpine glaciers. 
The peculiar assemblage of stones can nearly all be matched by rocks 
occurring in situ in the west of Scotland and in northern and western 
Ireland. It is further significant that the very formations that are absent 
from those areas, although covering large parts of England, are equally 
unrepresented in our collection. 
The researches of glacialists have now made out, from the direction of 
ice-markings on the solid rocks and the distribution of boulders, that ice, 
having its origin in the west of Scotland, forced its way on to the north of 
Ireland, and there combining with the native ice, split up into two branches, 
one of which filled the Irish Sea and made its way down so far south as to 
override part of Pembrokeshire on the one side and on the other to impinge 
upon the Irish shore to at least as far south-west as Cork. The other branch, 
passing westwards, made its way into the Atlantic, and reached the deep 
water at the edge of the continental shelf as portion of the ice-sheet that 
enveloped the greater part of Britain and the whole of Ireland at the period 
of maximum glaciation. 
It is to this period that we must look for the peculiar distribution of 
most of our rock-fragments by means of floating ice, for the evidence already 
adduced shows that the stones were dropped from above into globigerina ooze. 
Some small proportion of our material may have been floated off from our 
shores during the later part of the glacial period by pack-ice or ice-foot, 
which might account for the presence of so many angular, evidently frost- 
riven, splinters of dolerite ; while some of the rolled stones may even have 
been distributed by floating river ice drifted seawards during sudden thaws. 
A few of the smaller stones may have been transported by floating seaweed. 
Some of the material may even have been brought by part of the “ polar 
pack ” since glacial times, as an occasional small floe has been observed to 
approach within a few hundred miles of our shores, and it is perhaps to this 
source that we must look for the presence of the specimen of nepheline 
syenite. 
Some of the glaciated stones have nests of clay attached to them in which 
are rounded grains of quartz over one millimetre in diameter, much larger 
than those found in the ooze, which average only 0 09 mm. in diameter, 
showing that the clay is no part of the ooze, but must have been transported 
