194 
ISLAND LIFE. 
[part 1. 
and some of them can be traced to the Welsh hills from 
twenty to fifty miles distant. This remarkable formation was 
first pointed out as proving a remote glacial period, by Professor 
Ramsay ; and Sir Charles Lyell agreed that this is the only 
possible explanation, that, with our present knowledge, we can 
give of them. 
Permian breccias are also found in Ireland, containing blocks 
of Silurian and Old Red sandstone rocks which Professor Hull 
believes could only have been carried by floating ice. Similar 
breccias occur in the south of Scotland, and these are stated 
to be “ overlain by a deposit of glacial age, so similar 
to the breccia below as to be with difficulty distinguished 
from it.” 1 
These numerous physical indications of ice-action over a 
considerable area during the same geological period, coinciding 
with just such a poverty of organic remains as might be pro- 
duced by a very cold climate, are very important, and seem 
clearly to indicate that at this remote period geographical 
conditions were such as to bring about a glacial epoch in our 
part of the world. 
Boulder-beds also occur in the Carboniferous formation, both 
in Scotland, on the continent of Europe, and in North America; 
and Professor Dawson considers that he has detected true 
glacial deposits of the same age in Nova Scotia. Boulder-beds 
also occur in the Silurian rocks of Scotland and North America, 
and according to Professor Dawson, even in the Huronian, older 
than our Cambrian. None of these indications are however 
so satisfactory as those of Permian age, where we have the very 
kind of evidence we looked for in vain throughout the whole of 
the Tertiary and Secondary periods. Its presence in several 
localities in such ancient rocks as the Permian is not only most 
important as indicating a glacial epoch of some kind in Palaeozoic 
times, but confirms us in the validity of our conclusion, that the 
total absence of any such evidence throughout the Tertiary and 
Secondary epochs demonstrates the absence of recurring glacial 
epochs in the northern hemisphere, notwithstanding the frequent 
recurrence of periods of high excentricity. 
1 Geological Magazine, 1873, p, 320. 
