Switzerland. As from
the Bernese Oberland and from the valleys of the Reuss and Limmath
gigantic glaciers came down and stretched across the plain of
Switzerland to the Jura, scattering their erratic boulders over its
summit and upon its slopes at the time of their greater extension, and,
as they withdrew into the higher Alpine valleys, leaving them along
their retreating track at the foot of the Jura and over the whole plain,
so did the glaciers from Glen Prossen and parallel valleys on the
Grampian Mountains extend across the valley of Strathmore, dropping
their boulders not only on the slopes and along the base of the Sidlaw
Hills, but scattering them in their retreat throughout the valley, until
they were themselves reduced to isolated glaciers in the higher valleys.
At the same time other glaciers came down from the heights of
Schihallion on the west, and, descending through the valley of the Tay,
joined the great masses of ice in the valley of Strathmore, thus
combining with the eastern ice-field, just as the glacier from Mont
Blanc and the valley of the Rhone formerly combined in the western part
of Switzerland with those of the Bernese Oberland. The relations are
identical, though the geographical position is reversed,--the higher
range, or the Grampian Hills, lying to the north in Scotland, and the
lower one, or the Sidlaw Hills, to the south, while in Switzerland, on
the contrary, the higher range lies to the south and the lower to the
north. I have alluded especially to Glen Prossen because the glacial
marks in that valley are remarkably distinct, the whole bed of the
valley being scratched, polished, and furrowed by the great rasp which
has moved over it, while the concentric moraines at its lower extremity
are very striking. But these signs, so perfectly preserved in Glen
Prossen, recur with greater or less intensity in all the corresponding
valleys, leaving no doubt that the same phenomena existed over the whole
region.

Among the localities of Scotland where the indications of glacial action
are most marked is the region about Stirling. Near Stirling Castle the
polished surfaces of the rocks with their distinct grooves and scratches
show us the path followed by the ice as it moved down in a northeasterly
direction toward the Frith of Forth from the mountains on the northwest.
To the west of Edinburgh, also, there is a broad glacier-track, showing
that here also the ice was ploughing its way eastward to fi