MECHANICAL ACTION OF GLACIERS, 159 
a this time the Baltic communicated with the White 
ea. 
It is alleged that it was after the melting of the con- 
tinental ice, and while the glaciers were thus receding from 
their extension to the valleys, to the summits and elevated 
ridges, where they still maintain their position, that the 
transition issuing in the existing state of the country 
occurred, At about the same period the communications 
between the Baltic and the White Sea were interrupted, 
and the ground of the Scandinavian peninsula, in the 
southern part of Norway, was elevated about 160 metres, 
or 530 feet. Old shore lines, banks of marine shells, and 
sand terraces, supply indications, both in Norway and 
Sweden, of this having been the case, and prove at the same 
time that the elevation varied with time ; and that during a 
lengthened period it was a time of stagnation, perhaps even 
of subsidence. In Norway there exist banks of marine 
shells at, at least, two different altitudes, the one about 
150 metres, or about 500 feet, the other about 300 metres 
or 1000 feet, above the present level of the sea, With 
the origin of these heaps of shells we have not at present 
to deal; it is their position alone which here concerns us. 
The higher-lying banks contain Arctic shells ; the lower- 
lying ones northern shells, corresponding to the species 
which live at the present day along the coast. Consider- 
ing both to have been collected on the shore of the ocean 
—the upper heaps in days more remote, the lower ones in 
days nearer to our own, these heaps supply indications at 
once of an elevation of the land, and of the other pheno- 
mena referred to in connection therewith. In our own 
time the coasts of Sweden, on the Baltic, are supposed 
to be rising at the rate of a metre, or forty inches, in a 
hundred years. 
Old moraines exist at a succession of altitudes up to 
that of those which are being formed under our eyes— 
sometimes lying across the depth of the valley, terminal 
moraines; sometimes along the line of the water-courses, 
lateral moraines. Large moraines exist on the two sides of 
