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Updated: May 17, 2025
Signs of extinct Glaciers in England. Ice Action in Ireland. Maps illustrating successive Revolutions in Physical Geography during the Pleistocene Period. Southernmost Extent of Erratics in England. Successive Periods of Junction and Separation of England, Ireland, and the Continent. Time required for these Changes. Probable Causes of the Upheaval and Subsidence of the Earth's Crust.
Here, therefore, we have proof that the transport of erratics continued to take place, not merely when the sea was inhabited by the existing testacea, but when the north of Europe had already assumed that remarkable feature of its physical geography which separates the Baltic from the North Sea, and causes the Gulf of Bothnia to have only one- fourth of the saltness belonging to the ocean.
There are erratics some two or three hundred feet above this great moraine, showing that the glacier must have been more than five hundred feet thick when it left this accumulation of loose materials at such a height. It then united, however, with a large glacier more to the west.
The rock on which the boulder formation reposes, if it consists of granite, gneiss, marble, or other hard stone, capable of permanently retaining any superficial markings which may have been imprinted upon it, is usually smoothed or polished, like the erratics above described, and exhibits parallel striae and furrows having a determinate direction.
At its fulness, the great ice mass lay almost a mile in depth over New England, as attested by the scratched and polished rock surfaces and deposited erratics in the White Mountains. Such a mass presses down with a weight of about one hundred and twenty-five tons to the square foot, according to Dr. Croll's estimate.
Upon the top of this ridge repose several huge erratics, consisting of gneiss for the most part unrounded, from nine to sixteen feet in diameter, and which must have been brought into their present position since the time when the neighbouring gulf was already characterised by its peculiar fauna.
Mention is also made of blocks of granite which have travelled from south to north in Aberdeenshire, of which there would have been no examples had the erratics been all brought by floating ice from the arctic regions when Scotland was submerged.
The arrangement of the drift and erratics thus depicted accords perfectly well with Charpentier's views and is quite irreconcilable with the supposition of the scattered blocks having been dispersed by floating ice when Switzerland was submerged.
He thought it impossible that the glacial detritus of the Rhone could ever have been carried to the Lake of Geneva and beyond it by a glacier, or that so vast a body of ice issuing from one narrow valley could have spread its erratics over the low country of the cantons of Vaud, Fribourg, Berne, and Soleure, as well as the slopes of the Jura, comprising a region of about 100 miles in breadth from south-west to north-east, as laid down in the map of Charpentier.
Marine Shells in Scotch Glacial Drift. Their Arctic Character. Rarity of Organic Remains in Glacial Deposits. Contorted Strata in Drift. Glaciation of Wales, England, and Ireland. Marine Shells of Moel Tryfaen. Erratics near Chichester. Glacial Formations of North America. Many Species of Testacea and Quadrupeds survived the Glacial Cold.
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