1868. of Norway and Scotland. 465 
Whether therefore we investigate the physical position of the 
older glacial shell-beds of Scotland and Norway, their order and 
elevation, or their fossil contents, we find that they unfold a series 
of parallel phenomena, and suggest problems which refer to cos- 
mical causes rather than the accidents of local circumstance. 
II. The second great series of beds indicates a change from the 
extreme arctic conditions of the preceding period. 1. There are 
sufficient proofs, we believe, that the change of climate did not take 
place suddenly. ‘The phrase “ Raised Beaches” entirely fails to 
express the varying characteristics of the beds usually compre- 
hended by it. It is necessary to study each deposit by itself, and 
carefully catalogue the contents, with the proportions in which the 
species occur ; and different zones of marine life will frequently be 
found comprised under the general term “ Raised Beaches.” 
Many of the Norwegian beds contain a mingling of arctic species 
with a large development of those, now the common inhabitants of 
the neighbouring seas. 
The first characteristic indeed of these semi-glacial or post- 
glacial beds, is the very large increase in the number of species 
contained. Individual specimens may be as abundant in some 
glacial as in some later deposits, but invariably, species are far 
fewer in the more arctic clays. We previously quoted the fact, 
that Sars has collected fifty-nine species of mollusca from the 
glacial beds; from the succeeding series, he has catalogued 175. 
In these deposits also, both individual specimens of arctic 
species, as well as arctic species themselves, are less predominant. 
We have reached the period at which arctic forms have not left the 
waters, but have received a check, and are being driven northward 
to a more congenial clime. Magnificent examples of this class of 
beds occur near the small town of Skien, on the northern side of 
the Christiania fjord. 
At the south end of the beautiful lake Nordsaeen is a large 
shell bank, scattered in massive undulations over many acres. Its 
elevation is about 100 feet above the sea. It contains 128 species 
of mollusca, a number in itself far exceeding that contained in the 
whole of the older glacial clays. Among these 128 species, there 
are very few that may not be found living in Christiania fjord; but 
these few are arctic in character. For example, Pecten islandicus 
is small and rare; Tellina calcarea is large and tolerably abundant ; 
but some characteristic arctic species have disappeared. Leda 
arctica, and even Astarte borealis are absent; while the relative 
proportion of the remaining glacial forms has become entirely 
subordinate. 
The same phenomenon is developed in a large series of similar 
beds, spread over the west of Norway ; and appears conclusively to 
establish the gradual character of the climatic e. 5 
K 
