Relation of the Plant Population to the Glacial Period. 375 
parts of the south-west, are striated and covered by morainic 
material, the ice extending well out into the Atlantic. The 
icebergs were so big, or the ice-foot so thick, that, breaking 
away from the Irish coast, the masses were able to float across 
to the Scilly Isles before they melted; for they carried with 
them numerous striated stones of well-known rocks, now found 
stranded on the highest parts of the Isles of Scilly. Thus it 
is evident that in those days Scilly, our most southerly and 
warmest point, was surrounded by a bitterly cold ocean, and 
it was submerged to such an extent that it could be over- 
ridden by pack-ice. Could any temperate plant survive such 
treatment ? I particularly want you to realise the climate 
that Scilly enjoyed in these days, for it is now one of the warmest 
spots in our islands, and its temperate flora has come back, 
though the islands are surrounded by fairly deep sea. 
It seems evident, therefore, that a temperate flora could 
not have survived the cold in Ireland or in the Scilly Isles. 
But there is still the non-glaciated area south of the Severn 
and Thames to consider, and botanists may tell us that the 
temperate flora survived in some warm nooks in Devon or 
the Isle of Wight. Here, however, we can point to evidence 
that the botanist himself must accept as conclusive. 
In the south of Devon one of the warmest of the sheltered 
valleys is that through which the Teign flows to Newton Abbot. 
But in the alluvial deposits of this valley, and only a few feet 
above the sea-level, Professor Oswald Heer and Professor 
Nathorst discovered leaves of the dwarf Arctic birch and some 
Arctic mosses. 
Time will not allow us to go into all the evidence; so I 
will only point to one or two other areas which prove the 
extreme rigour of the climate in the south of England. Close 
to Salisbury are found in profusion remains of various Arctic 
mammals—reindeer, musk-ox, Arctic fox, lemming, and 
several others. Unfortunately plants do not seem to have been 
searched for, and the sections were obscured when I visited 
the pit; however, the flora associated with this assemblage 
of mammals can only have been the flora of the Arctic regions. 
Around Portsmouth we have abundant evidence of this - 
icy sea, for in the peninsula of Selsey especially we find numerous 
large erratic blocks floated by ice. Some of them have been 
identified as coming from the Isle of Wight, others from Bognor 
and Cornwall, and a number came from the Channel Islands. 
Thus even the north coast of France had its shores fringed with 
ice. 
I have attempted to show on a map* what the Channel 
was like when Spithead was thus blocked with ice-floes. Is it 
* Exhibited at the meeting. 
to1t Nov. 1. 
