Eberhard Grüger

An attempt at correlation between the Velay pollen sequence and the Middle Pleistocene stratigraphy from central Europe

Abstract Long continuous lacustrine sequences constitute on the continent a precious tool for coupling the long term continental environmental changes with deep sea and ice core records, using the ‘count from the top’ method. Moreover, they can contribute to long distance correlation on the continent itself and thus help to classify discontinuous sedimentary records. Palynostratigraphical correlation is proposed here between the Velay long sequence and the late Middle Pleistocene series from Central Europe with special attention to temperate episodes. The similarities between the Praclaux and the Holsteinian Interglacial suggest that they are both contemporaneous with marine isotopic stage (MIS) 11, even if absolute dates are still divergent. The evidence of two major warm periods with an interglacial type of vegetation between the Holsteinian and the Eemian is confirmed by the Velay record.

European vegetation during Marine Oxygen Isotope Stage-3

European vegetation during representative “warm” and “cold” intervals of stage-3 was inferred from pollen analytical data. The inferred vegetation differs in character and spatial pattern from that of both fully glacial and fully interglacial conditions and exhibits contrasts between warm and cold intervals, consistent with other evidence for stage-3 palaeoenvironmental fluctuations. European vegetation thus appears to have been an integral component of millennial environmental fluctuations during stage-3; vegetation responded to this scale of environmental change and through feedback mechanisms may have had effects upon the environment. The pollen-inferred vegetation was compared with vegetation simulated using the BIOME 3.5 vegetation model for climatic conditions simulated using a regional climate model (RegCM2) nested within a coupled global climate and vegetation model (GENESIS-BIOME). Despite some discrepancies in detail, both approaches capture the principal features of the present vegetation of Europe. The simulated vegetation for stage-3 differs markedly from that inferred from pollen analytical data, implying substantial discrepancy between the simulated climate and that actually prevailing. Sensitivity analyses indicate that the simulated climate is too warm and probably has too short a winter season. These discrepancies may reflect incorrect specification of sea surface temperature or sea-ice conditions and may be exacerbated by vegetation–climate feedback in the coupled global model.

FIRST RESULTS OF BIOSTRATIGRAPHICAL INVESTIGATIONS OF LAGO D’AVERNO NEAR NAPLES RELATING TO THE PERIOD 800 BC–800 AD

Abstract Remains of diatoms, molluscs, ostracods, foraminifera and pollen exines preserved in the sediments of Lago d’Averno, a volcanic lake in the Phlegrean Fields west of Naples, allowed us to reconstruct the changes in the ecological conditions of the lake and of the vegetation around it for the period from 800 BC to 800 AD. Lago d’Averno was at first a freshwater lake, temporarily influenced by volcanic springs. Salinity increased slowly during Greek times as a result of subsidence of the surrounding land. Saline conditions developed only after the lake was connected with the sea by a canal, when Portus Julius was built in 37 BC. The first post-Roman period of uplift ended with a short freshwater phase during the 7th century after Christ. Deciduous oakwoods around the lake was transformed into a forest of evergreen oaks in Greek times and thrived there — apparently almost uninfluenced by man — until it was felled, when the Avernus was incorporated into the new Roman harbour in 37 BC, to construct a shipyard and other military buildings there. Land-use was never more intense than during Roman times and weakest in Greek and Early Roman times, when the Avernus was considered a holy place, the entrance to the underworld.

Palynostratigraphy of the last interglacial/glacial cycle in Germany

Abstract The last interglacial/glacial cycle comprises the Eemian and the Weichselian (in the area of the Scandinavian Glaciation), respectively the Riss/Wurm and the Wurm (in southern Germany). Drastic changes of the vegetation have occurred several times during this period in Europe. The best known in Germany is the development of the forests of the last interglacial stage and of the two succeeding early-glacial interstadial phases, the Brorup and the Odderade. Above the Odderade, sediments of two more (Middle Weichselian) interstadials, the Oerel and the Glinde, with a shrub-tundra vegetation have been found at one site in northern Germany. In southern Germany the palynological record ends somewhat earlier, i.e. with the equivalent of the Oerel interstadial, which here in the south had a forest vegetation. Numerous single occurrences of interstadial sediments of different age and vegetation have been studied, but unfortunately their stratigraphic position is most frequently unclear. Therefore a general survey can only rely on few, but long sequences. Their comparison shows that vegetational gradients of different steepness existed at different times, which mirror the changing climatic gradients of this period. The main points of the vegetational zonation as far as it is known from Germany for the cycle are summarized.