170 
ISLAND LIFE. 
[part I. 
an entire country there would be no moraines, and that rocks or 
ddbris are very rarely seen on icebergs. But during every 
glacial epoch there will be a southern limit to the glaciated 
area, and everywhere near this limit the mountain-tops will 
rise far above the ice and deposit on it great masses of debris ; 
and as the ice-sheet spreads, and again as it passes away, 
this moraine-forming area will successively occupy the whole 
country. But even such an ice-clad country as Greenland is 
now known to have protruding peaks and rocky masses which 
give rise to moraines on its surface ; 1 and, as rocks from Cumber- 
land and Ireland were carried by the ice-sheet to the Isle of Man, 
there must have been a very long period during which the ice- 
sheets of Britain and Ireland terminated in the ocean and sent 
off abundance of rock -laden bergs into the surrounding seas; 
and the same thing must have occurred along all the coasts of 
Northern Europe and Eastern America. 
We cannot therefore doubt that throughout the greater part 
of the duration of a glacial epoch the seas adjacent to the 
glaciated countries would receive continual deposits of large 
rocks, rock-fragments, and gravel, similar to the material of 
modern and ancient moraines, and analogous to the drift and the 
numerous travelled blocks which the ice has undoubtedly scat- 
tered broadcast over every glaciated country; and these rocks 
and boulders would be imbedded in whatever deposits were then 
forming, either from the matter carried down by rivers or from 
the mud ground off the rocks and carried out to sea by the 
glaciers themselves. Moreover, as icebergs float far beyond the 
limits of the countries which gave them birth, these ice-borne 
materials would be largely imbedded in deposits forming from 
the denudation of countries which had never been glaciated, or 
from which the ice had already disappeared. 
But if every period of high excentricity produced a glacial 
epoch of greater or less extent and severity, then, on account of 
the frequent occurrence of a high phase of excentricity during 
the three million years for which we have the tables, these 
boulder and rock-strewn deposits would be both numerous aud 
extensive. Four hundred thousand years ago the excentricity 
1 Nature , Yol. XXI., p. 345, “The Interior of Greenland.” 
