In its broad outlines the prehistory of Europe from the close of the Palaeolithic Age is a record of (1) a series of profound climatic changes, producing modifications of culture and the settlement of new areas; (2) a series of cultural influences coming in from Asia and Africa; (3) a series of invasions of new peoples from Asia and Africa; and (4) the formation of new peoples and the development of new cultures as a result of the interaction of these major factors.(1) Climatic Changes and Time-Scale
By counting and comparing the varves, or annual layers of gravel and clay laid down in post-glacial lakes in many parts of the Baltic area, archaeologists have been able tentatively to tell the year in which each layer was formed over a period covering the past 10,000 years. The thickness of the varves and an analysis of the pollen contained in them and other deposits furnish a record of the progressive climatic changes year by year and date with reasonable accuracy typical archaeological remains found in some clear relation to these deposits. This gives a basic time-scale for northern Europe, which can be applied (in a general way and with modifications) to the rest of Europe, and can be checked, for the later periods, against tentative dates determined archaeologically on the basis of contacts with the historical cultures of Mesopotamia, Egypt, Greece, and Rome.
Following is the sequence of climatic periods in the Baltic region:
8300 B.C. Sub-Arctic period. Contemporary with the Gotiglacial stage of the ice retreat and end of the Palaeolithic period. Very cold and characterized by Dryas flora, dwarf birch, willow, and tundra and steppe types of animals. 8300-6800. Pre-Boreal period. Contemporary with the Finiglacial stage of the ice retreat, the Yoldia Sea and first half of the Ancylus Lake phase of the Baltic and the beginning of the Mesolithic period. Less cold, and characterized by birch, pine, and willow trees and mixed tundra and forest types of animals.
6800-5600. Boreal period. Post-glacial and contemporary with the last half of the Ancylus Lake phase of the Baltic. Rise in sea-level. Cool, dry “continental” climate, with birch and pine dominant, but alder and oak-mixed forest coming in and animals mostly of forest and lake type.
5600-2500. Atlantic period. Contemporary with the transgression of the Litorina Sea in the Baltic. Sea-level still high. Warm and moist “oceanic” climate (the so-called period of climatic optimum), with alder and oak-mixed forest (oak, elm, and lime) dominant, and forest, lake, and sea types of animals.
2500-700. Sub-Boreal period. Land relatively stable with relation to the sea and the Baltic Sea largely landlocked as at present. Dry, warm climate.
700- Sub-Atlantic period. Wet, cold climate.