CHAPTER XV.
EXTINCT GLACIERS OF THE ALPS AND THEIR CHRONOLOGICAL RELATION TO THE HUMAN PERIOD.
EXTINCT GLACIERS OF SWITZERLAND—ALPINE ERRATIC BLOCKS ON THE JURA—NOT TRANSPORTED BY FLOATING ICE—EXTINCT GLACIERS OF THE ITALIAN SIDE OF THE ALPS—THEORY OF THE ORIGIN OF LAKE-BASINS BY THE EROSIVE ACTION OF GLACIERS, CONSIDERED—SUCCESSIVE PHASES IN THE DEVELOPMENT OF GLACIAL ACTION IN THE ALPS—PROBABLE RELATION OF THESE TO THE EARLIEST KNOWN DATE OF MAN—CORRESPONDENCE OF THE SAME WITH SUCCESSIVE CHANGES IN THE GLACIAL CONDITION OF THE SCANDINAVIAN AND BRITISH MOUNTAINS—COLD PERIOD IN SICILY AND SYRIA.
Extinct Glaciers of Switzerland.
WE have seen in the preceding chapters that the mountains of Scandinavia, Scotland, and North Wales have served, during the glacial period, as so many independent centres for the dispersion of erratic blocks, just as at present the ice-covered continent of North Greenland is sending down ice in all directions to the coast, and filling Baffin's Bay with floating bergs, many of them laden with fragments of rocks.
Another great European centre of ice-action during the post-pliocene period was the Alps of Switzerland, and I shall now proceed to consider the chronological relations of the extinct Alpine glaciers to those of more northern countries previously treated of.
The Alps lie far south of the limits of the northern drift described in the foregoing pages, being situated between the 44th and 47th degrees of north latitude. On the flanks of these mountains, and on the subAlpine ranges of hills or
