a 
Part V. Secr. i. § 1.] PLEISTOCENE. | 885 
nana, &c. (Vig. 425). These relics of a terrestrial vegetation are 
drifted specimens, but they cannot have travelled far, and they 
probably represent a portion of the Arctic flora which had already 
found its way into the middle of England before the advent of the 
ice-sheet. Judging from the present distribution of the same plants, 
we may infer that the climate had become about 20° colder than it 
was during the time represented by the Forest-bed—a difference as 
ereat as that between Norfolk and the North Cape at the present 
day.’ 4 
Ice-worn Rocks.—At the base of the glacial deposits the 
solid rocks over the whole of northern Hurope present the charac- 
teristic smoothed flowing outlines produced by the grinding action 

Fig. 425.—Arcric PLANTS FRoM GLACIAL Bens. 
a, Salix polaris (Wahlenb.) (3); 6, Betula nana (Linn.); c, Leaf of same, showing the 
size to which it grows in more southern countries. 
of land-ice (p. 413). Long exposed, this peculiar surface is apt to 
be effaced by the disintegrating action of the weather, though it 
retains its hold with extraordinary pertinacity. Along the fjords of 
Norway and the sea-lochs of the west of Scotland, it may be seen 
slipping into the water, smooth, bare, polished, and grooved as if the 
ice had only recently retreated. Inland, where a protecting cover 
of clay or other superficial deposits has been newly removed, the 
peculiar ice-worn surface is as fresh as that by the side of a modern 
glacier. Observations of the directions of the strize have shown © 
that on the whole these markings diverge from the main masses of 
high ground. This radiation is admirably seen in the British 
Islands, where each block of elevated land, such as the Grampians, 
the southern uplands of Scotland, and the hills of the Lake district, 
served as centres whence the ice flowed downwards and outwards in 
all directions into the plains or into the sea. In Scandinavia the 
ice-strie run westwards and south-westwards on the Norwegian 
coasts, and eastwards or south-eastwards across the lower grounds of 
1 C. Reid, Horizontal Section, No. 127 of Geol, Survey, and Memoir on Cromer 
district in Memoirs of Geol. Survey. 
