The Early Glacial period ca BP

It is now clear that the earlier stages of the last glacial period were characterized by a complex but clearly defined pattern of climatic oscillations. In the isotope records of deep-sea cores (Fig. 2.1) this period comprised four main stages, of which two, stages 5d and 5b, were quite clearly glacial in character while the other two, 5c and 5a, were much warmer 'interstadial' episodes marked by a sharp increase in world-wide temperature conditions and a corresponding reduction in the overall extent of glaciation (Shack-leton 1977, 1987). Collectively, this sequence of major climatic fluctuations occupies a period of around 40,000 years, from ca 118,000 to ca 75,000 BP.

The character of climatic and ecological conditions during the so-called 'early glacial' or 'early Weichselian' is now well documented in many parts of western and central Europe from the long and continuous pollen sequences recorded at La Grande Pile (Fig. 2.6), Les Echets (Fig. 2.7), Padul, Tenaghi Pillipon, Valle di Castiglione and several other localities (Woillard 1978; de Beaulieu & Reille 1984; Reille & de Beaulieu 1990; Flor-schuz et al 1971; Wyjmstra et al 1990; Follieri et al 1989). Following much debate there is now effective agreement as to how these sequences should be correlated with the oxygen-isotope records in ocean cores. The two major warm periods represented in the Grande Pile and Les Echets diagrams (i.e. St Germain interstadials I and II) clearly correlate with the major periods of deglaciation represented in isotope stages 5c and 5a, while the intervening colder periods (Melisey stages I and II) correlate with the major phases of glacial advance in stages 5d and 5b (Fig. 2.6) (Woillard & Mook 1982; de Beaulieu & Reille 1984; Zagwijn 1990; Behre 1990; Behre & Plicht 1992; LIGA 1991a).

Support for this correlation has been provided by the analysis of sea-bed sediments just to the west of the Spanish coast, where a characteristic series of pollen-zone assemblages can be correlated directly with parallel fluctuations of the 180/160 record of the deep-sea sediments themselves (Turon 1984). In the more northern parts of Europe there is now equal agreement that the well known

Depth 0 A P Percentage 100 Climatic Stage Isotope Age B P

Depth 0 A P Percentage 100 Climatic Stage Isotope Age B P

Beaulieu Reille Grande Pile

Figure 2.6 Vegetational sequence recorded in the long pollen core from La Grande Pile in the Vosges region of northeastern France, covering the period of the last interglacial and glacial cycle. The dates for the upper part of the sequence (post 70,000 BP) are based on radiocarbon measurements, while those for the lower part are based on the inferred correlations with the isotopic stages in deep-sea cores. The names given to the major stadial and interstadial phases in the sequence are indicated in the central column. After Woillard & Mook 1982.

Figure 2.6 Vegetational sequence recorded in the long pollen core from La Grande Pile in the Vosges region of northeastern France, covering the period of the last interglacial and glacial cycle. The dates for the upper part of the sequence (post 70,000 BP) are based on radiocarbon measurements, while those for the lower part are based on the inferred correlations with the isotopic stages in deep-sea cores. The names given to the major stadial and interstadial phases in the sequence are indicated in the central column. After Woillard & Mook 1982.

succession of Amersfoort, Brorup and Odd-erade interstadials can be correlated closely with the vegetational sequences at La Grande Pile, Les Echets and elsewhere, with the Amersfoort and Brorup intervals corresponding essentially with the earlier and later parts of the St Germain I interstadial (see below) and the Odderade interstadial with the major warming during St Germain II (Figs 2.9, 2.10) (Zagwijn 1990, de Beaulieu & Reille 1984; Behre 1990; Behre & Plicht 1992). Several interstadial deposits recorded in southern Britain (at Chelford, Wretton and elsewhere) most probably correlate with the period of St Germain I (Bowen 1990; Simpson & West 1958; West et al 1974).

Les ECHETS-G Altitude 2671

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