* 
172 + “GEOLOGY. 
climate became milder, and Britain looked like Norway and Iceland, with 
glaciers on the higher grounds, reaching here and thereto the sea. Gradu- 
ally the great ice-fields melted away under the rays of the genial sun, and 
our country looked like the present Switzerland, till at length the last 
glacier disappeared from the highest hills. The effects ofvall the wear and 
movement of these ice-masses, whether grinding down the land or grating 
on the floor of the ocean, or dashing against opposing islands, are seen in 
the thick clay and sand deposits everywhere around us,’enclosing worn 
stones and gravel ; the scratched and rounded rock-surfaces often bright 
and smooth as "polished marble; the ‘ erratic boulders,’ perched on our 
\d plains ; and the general wavy outline of all higher ground 
our land. This glaciation has been ascertained to extend over 
the whole of Northern Europe and America, and round the shores of the 
Antarctic Ocean. 








XII—Quaternary or Recent Period. 
We have now reached the last of the great geological epochs, during 
. . : . ‘ 
which sea and land, plants and animals, have remained little changed 
from what they are now. This last system has been variously named the 
Post Tertiary, Quaternary, or Recent 
The whole system may be divided into two chief periods : 
1. The Prehistoric, or that before history was written. 
2. The Historic, or that since history was written. 
- During the le epoch, there is little or no solid rock, the whole 
deposits consistingof clay, sand, gravel, mud, peat, and the like. 
Of prehistoric deposits, we find such remains as these: plants of alk 
kinds, all common shells and corals, and common animals, with a few now 
extinct, such as the long-fronted ox, the gigantic Irish deer—a creature ten 
fect high to the top of its hase ‘elephant, rhinoceros, hyena, bear, 
and mammoth, besides human remains in bones, canoes, aaa dwellings, 
and weapons. 
In historical times, we find similar remains, but the deposits are 
comparatively small; and the plant and animal remains are almost solely 
those now existing in each country. Men have left traces of themselves 
in buildings, colns, implements, weapons, and works of art; while peat- 
bogs ‘have been formed, forests have been submerged or cut down, and 
eo dtedile changes in den, lero have taken ] e. 
Since the glacial epoch, a continuous series of changes has been going 
on without intermission, accomplished by various causes and im various 
ways. The land has changed its ak several times both by elevation and 
depression, the sea Se alternatel ching on and retiring from the 
land. Whale goats s ii 4 {i ned from the ocean, such as the Fens 
¢ 

