3. The Bühl stage of Postglacial advance in the Alps; renewal of severe conditions of cold moist climate, and spread all over western Europe of the arctic banded and Obi lemmings of the Upper Rodent Layer. Bühl moraines in Lake Lucerne estimated as having been deposited between 16,000 and 24,000 years B. C. Crô-Magnon race dominant in the Early Magdalenian stage of culture.
2. Period of the first Postglacial interval or Achen retreat of the glaciers in the Alpine region. A dry cold climate. Crô-Magnon and Brünn races in the stage of Solutrean culture.
1. Close of fourth glaciation, between 24,000 and 40,000 years B. C. Cold and moist but increasingly dry climate succeeding the fourth glaciation and deposition of Lower Rodent Layer, or first invasion of the arctic tundra rodents. Crô-Magnon and possibly Aurignacian race in the stage of Aurignacian culture.
BEGINNING OF THE UPPER PALÆOLITHIC
The Aurignacian Industry
We now glance at western Europe as it was between 25,000 and 30,000 years ago, at the opening of the Upper Palæolithic.
During Aurignacian times France was still broadly connected with Great Britain.[(11)] The British Islands were not only united with each other but with the continent, while the elevation of the Scandinavian peninsula converted the Baltic Sea into a great fresh-water lake, the old shores of which are readily traced. Geikie also maintains that the rise of land in Scotland after the fourth glaciation was accompanied by an amelioration of climate and the advent of more genial conditions; a strong forest growth covered the lowlands, hence this is termed the Lower Forestian stage of the physiographic history of northern Britain; it corresponds to the temporary period of the retreat of the glaciers in the Alpine region, which Penck has named the Achenschwänkung. The latter author is not inclined to connect any marked rise of temperature in the Alpine region with this interval of time; to our knowledge no fossil plant beds have been preserved which would give us such indications, and the animal life, as we shall see, certainly affords only a very slight indication of a rise in temperature in the retreat of certain of the snow-loving tundra and northern steppe lemmings to the north; the greater number of tundra forms remained. The continental elevation of the northern coast-line of Europe would explain the advent of a dry continental climate and the renewal of high prevailing winds, at least during the warmer and drier summer seasons, for it is certain that atmospheric conditions such as produced the great dust-storms and deposition of 'loess' after the second and third glaciations prevailed again in western Europe after the fourth glaciation. This gave rise to deposits of what is known among geologists as the 'newer loess,' and we find these sheets of 'newer loess' spreading immediately above the Mousterian culture at a number of different points in western Europe.
When the Crô-Magnon race entered this part of Europe the climate was becoming more dry and stimulating; the summers were warm or temperate, the winters very severe. Great ice-caps still spread over the Scandinavian peninsula and also over the Alps, but the borders of the ice-fields no longer reached the plains; in a sense, the Glacial Epoch had not yet closed, for during the whole period of Postglacial time the glaciers of the Alps, beginning in early Magdalenian times, developed three renewed advances, each somewhat less vigorous than the preceding one, with intervening stages of a drier climate.
Fig. 137. 'Tectiforms'—schematic drawings in lines and dots believed to represent huts and larger shelters built of logs and covered with hides. From the walls of the cavern of Font-de-Gaume, Dordogne. After Breuil.