Man and the Glacial Period

by G. Frederick Wright

Northern Europe.

On passing over the shallow German Sea from England to the Continent, the southern border of the Scandinavian ice-field is found south of the Zuyder Zee, between Utrecht and Arnhem—the moraine hills in the vicinity of Arnhem being quite marked, and a barren, sandy plain dotted with boulders and irregular moraine hills extending most of the way to the Zuyder Zee. From Arnhem the southern boundary of the great ice-field runs “eastward across the Rhine Valley, along the base of the Westphalian Hills, around the projecting promontory of the Hartz, and then southward through Saxony to the roots of the Erzgebirge. Passing next southeastward along the flanks of the Riesen and Sudeten chain, it sweeps across Poland into Russia, circling round by Kiev, and northward by Nijni-Novgorod towards the Urals.”[BV] Thence the boundary passes northward to the Arctic Ocean, a little east of the White Sea.

[BV] A. Geikie’s Text-Book of Geology, p. 885.

The depth of this northern ice-sheet is proved to have been upwards of 1,400 feet where it met the Hartz Mountains, for it has deposited northern débris upon them to that height; while, as already shown, it must have been over 2,000 feet in the main valley of Switzerland. In Norway it is estimated that the ice was between 6,000 and 7,000 feet thick.

The amount of work done by the continental glaciers of Europe in the erosion, transportation, and deposition of rock and earthy material is immense. According to Helland, the average depth of the glacial deposits over North Germany and northwestern Russia is 150 German feet, i. e., about 135 English feet. As the deposition towards the margin of a glacier must be commensurate with its erosion near the centre of movement, this vast amount implies a still greater proportionate waste in the mountains of Scandinavia, where the area diminishes with every contraction of the circle. Two hundred and fifty feet is therefore not an extravagant calculation for the amount of glacial erosion in the Scandinavian Peninsula.

It is not difficult to see how the Scandinavian mountains were able to contribute so much soil to the plains of northern Germany and northwestern Russia. Previous to the Glacial period, a warm climate extended so far north as to permit the growth of semi-tropical vegetation in Spitsbergen, Greenland, and the northern shores of British America. Such a climate, with its abundant moisture and vegetation, afforded most favourable conditions for the superficial disintegration of the rocks. When, therefore, the cold of the Glacial period came on, the moving currents of ice would have a comparatively easy task in stripping the mantle of soil from the hills of Norway and Sweden, and transporting it towards the periphery of its movement. Of course, erosion in Scandinavia meant subglacial deposition beyond the Baltic. Doubtless, therefore, the plains of northern Germany, with their great depth of soil, are true glacial deposits, whose inequalities of surface have since been much obliterated, through the general influences of the lapse of time, and by the ceaseless activity of man.

An interesting series of moraines in the north of Germany, bordering the Baltic Sea, was discovered in 1888 by Professor Salisbury, of the United States Geological Survey. Its course lies through Schleswig-Holstein, Mecklenburg, Potsdam (about forty miles north of Berlin), thence swinging more to the north, and following nearly the line between Pomerania and West Prussia, crossing the Vistula about twenty miles south of Dantzic, thence easterly to the Spirding See, near the boundary of Poland.

Among the places where this moraine can be best seen are—“1. In Province Holstein, the region about (especially north of) Eutin; 2. Province Mecklenburg, north of Crivitz, and between Bütow and Kröpelin; 3. Province Brandenburg, south of Reckatel, between Strassen and Bärenbusch, south of Fürstenberg and north of Everswalde, and between Pyritz and Solden; 4. Province Posen, east of Locknitz, and at numerous points to the south, and especially about Falkenburg, and between Lompelburg and Bärwalde. This is one of the best localities. 5. Province West Preussen, east of Bütow; 6. Province Ost Preussen, between Horn and Widikin.”

Comparing these with the moraines of America, Professor Salisbury remarks: