1877J The Great Ice Age and Origin of the "Till.” 
227 
re-examined them in the light of more recent information. 
Some few are alluvial, but they are exceptional and of 
minor magnitude. As an example of such alluvial terraces 
I may mention those near the mouth of the Romsdal, that 
are well seen from the Aak Hotel, and which a Russian 
prince, or other soldier merely endowed with military eyes, 
might easily mistake for artificial earthworks eredted for the 
defence of the valley. 
In this case, as in the others where the terraces are allu- 
vial, the valley is a narrow one, occupied by a relatively 
wide river loaded with recent glacial debris. It evidently 
filled the valley during the period of glacial recession. 
The ordinary wider valleys, with a river that has cut a 
narrow channel through the outspread terrace-fiats, display 
a different formation. Near the mouth of such valleys I 
have seen cuttings of more than a hundred feet in depth, 
through an unbroken terrace of most characteristic till, 
with other terraces rising above it. This is the ordinary 
constitution of the lower portions of most of the Scandina- 
vian terraces. 
These terraces are commonly topped with quite a different 
stratum, which at first I regarded as a subsequent alluvial 
or esturine deposit, but further examination suggested ano- 
ther explanation of the origin of some portions of this 
superficial stratum, to which I shall refer hereafter. 
These terraces prove a rise of sea or depression of land, 
during the glacial epoch, to the extent of 600 feet as a 
minimum, while the well-known deposits of Ardtic shells at 
Moel Tryfaen and the accompanying drift have led Prof. 
Ramsay to estimate “ the probable amount of submergence 
during some part of the glacial period at about 2300 feet.’ ? * 
It would be out of place here to reproduce the data upon 
which geologists have based their rather divergent opinions 
respecting the adtual extent of the submergence of the 
western coast of North Europe. All agree that a great sub- 
mergence occurred, but differ only as to its extent, their 
estimates varying between 1000 and 3000 feet. 
There is one important consideration that must not be 
overlooked, viz., that — if my view of the submarine origin 
of the till be correct — -the mere submergence of the land at 
the glacial period does not measure the difference between 
the depth of the sea at that and the present time, seeing 
that the deposits from the glaciers must have shallowed it 
very materially. 
* 
o 2 
Lyell, Elements of Geology, p. 159. 
