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view, glaciers assume an entirely new importance, for they introduce 
a long period of intense cold between the present epoch and that 
during which the animals existed, whose remains are buried in the 
usually called diluvial detritus. 
Having established his theory as completely as he could, by re- 
peated investigations of Switzerland and the adjacent portions of 
France and Germany, M. Agassiz became desirous of investigating 
a country in which glaciers no longer exist, but in which traces of 
them might be found. ‘This opportunity he has recently enjoyed, 
by examining a considerable part of Scotland, the north of England, 
and the north, centre, west and south-west of Ireland; and he has 
arrived at the conclusion, that great masses of ice, and subsequently 
glaciers, existed in these portions of the United Kingdom at a period 
immediately preceding the present condition of the globe, founding 
his belief upon the characters of the superficial gravels and erratic 
blocks, and on the polished and striated appearance of the rocks in situ. 
M. Agassiz does not suppose that) his views respecting glaciers 
will at once meet with the general concurrence of geologists; and 
he admits that the study of the phenomena of glaciers in different 
latitudes, as well as at different altitudes, together with the exami- 
nation of their different: effects where in contact with the sea, will 
introduce many modifications in the consideration of analogous 
phzenomena in countries where glaciers have disappeared ; but he is 
prepared to discuss his theory within the limits of observed facts, 
conscious of having searched for truth solely to advance the interests 
of science. RE 
To avoid useless discussion, he states, that in attributing to the 
action of glaciers a considerable portion of the results hitherto 
ascribed exclusively to that of water, he does not wish to maintain 
that everything hitherto assigned to the agency of water has been 
produced. by glaciers ; he only wishes that a distinction may be made 
in each locality between the effects of the different agents; and he 
adds, that long-continued practice has taught him to distinguish 
easily, in most cases, the effects produced by ice from those produced 
by water. ILIA 
Proceeding to the consideration of facts, he says the distribution 
of blocks and gravel, as well as the polished and striated surfaces of 
rocks in situ, do not indicate the action of a mighty current flowing 
from north-west to south-east, as the blocks and masses of gravel 
everywhere diverge from the central chains of the country, following 
the course of the valleys. Thus in the valleys of Loch Lomond and 
Loch Long, they range from north to south; in those of Loch Fine 
-and Loch Awe from north-west to south-east; of Loch Etine and 
Loch Leven from east to west; and in the valley of the Forth from 
north-west to south-east, radiating from the great mountain masses 
between Ben Nevis and Ben Lomond. - Ben Nevis in the north of 
Scotland, and the Grampians-in the south, are considered by the 
author to constitute the great centres of dispersion in that kingdom; 
and the mountains of Northumberland, Westmoreland, Cumber- 
land, and Wales; as well as those of Ayrshire, Antrim, the west of 
‘ 
