297 20 PALYNOLOGY OF THE QUATERNARY IN TEMPERATE AND TROPICAL AREAS: CHRONOSTRATIGRAPHY, PALAEOCLIMATOLOGY AND VEGETAL PALAEOENVIRONMENT OF FOSSIL MAN JOSETTE RENAULT-MISKOVSKY" and ANNE-MARIE SEMAH* + Unité de Palynologie du Laboratoire de Préhistoire du MNHN, Institut de Paleontologie humaine, 1, Rue René Panhard 75013, Paris, France # Uniié de Palynologie du Laboratoire de Préhistoire du MNHN, Institute de Paleontologie humaine, Orstom, Nouméa, B.P. A5, Nouvelle-Calédonia. I. PALYNOLOGY Palynology is the study of the shape and meaning of spores and pollen grains, which provide knowledge of fossil plants and reconstruction of their history. Plants produce thousands of spores and pollen grains each year, most of which are lost for reproduction ydare carried at ground level through different vehicles: wind, water, insects, mammals, and even men. Therefore, when the palaeobotanist takes sediments in a site, he collects, at the same time, whatever pollen amount is contained in them. The matters propitious to pollen analysis are mainly the deposits that ensure a good preservation of pollen grains, such as peatbogs, lacustrine and marine deposits. Archaeological deposits are also particularly useful to palaeoclimatic study; their place in time can be I identified out of human remains, manufactured objects and the degree of evolution of the faunae involved. Additional precision is given to the chronological scale by palaeomagnetic studies and the different radiometric methods of absolute datation. Samplings in aquatic or sub-aquatic media (peats, lacustrine muds or conchitic sands) are done in continuous series through boring and coring. However, prehistorical stratigraphies, most often established in dry milieu involve samplings in light deposits, such as clays, sands, gravel, I .I . - __ ---- - --- Traductions : Jacqueline GAUDEY and Elise HUFFER. I 298 / Current Concepts in Pollen-Spore and Biopollution Research or even deposits consolidated into brecciae along vertical sections cut 'during excavation (Girard, 1975). In the case of indurated deposits (stalagmitic floors], sampling is made by local sawing of blocks and columns, which are more finely cut in the laboratory afterwards. These conventional techniques have been recently completed by the techniques of deep coring throughout the deposits not yet excavated. It may be necessary to take samples in such special material as burials, vases for offerings, coating, or content of mummies, so as to relate a plant deposit, if any, to cultural and even ritual practice. Whatever the gathering, it must Be done quite properly to avoid any contamination. Sample preparation depends on the mineralogical composition of the deposit, but the principle of the most current method, called classical chemical method, consists in sieving oÜt, then dissolving in acids and bases, the mineral and organic matters in which spores and pollen grains are enclosed. As archeological sediments are rarely very fossiliferous, they have to be treated with a special concentration process, based on separating the grains from the rest of the gangue through floatation in dense solution, zinc chloride or Thoulet's liquor (Girard and Renault- Miskovsky, 1969).' The extraordinary properties of the membrane surrounding the grains, or exine, allow them to resist all the chemical corrosioh specific to preparation methods, and also to last almost indefinitelyI sheltered from oxidation through geological times; the grain structure, size, shape, the arrangement, type and number of germinal apertures, and also the exine sculpture, lead to identification of a plant family, genus or even species under the microscope. As a matter of fact, each plant species is represented by one type of grain, which is dete&ed by comparison to one modem grain, as spores and pollen grains have not evolved since modem florae settled on the earth. / Fossil grains, after being determined under the photon microscope, ' are counted. On the basis of statistical calculations, the percentages of the different categories can be referred to the total number of grains collected for a certain weight of the sample (20 to Sog]. This is pollen i analysis per level. Each spectrum per level is connected to its neighbour, and thus a pollen diagram is drawn that groups together all the evolu- tion curves of the different species throughout the sequence, including a 'global curve that enables assessment, at each level, of the proportion of I arboreal cover (AP : Arboreal Pollen) to herbaceous stratum (NAP : Non- Arboreal Pollen). The pollen diagram, based on the, principle that the general curve of the proportions of arboreal pollen to non-arboreal pollen indicates the importance of forests compared to open spaces in European ldw and . middle-altitude areas, reveals a sequence of landscapes subjected to climate evolution. Palynology of the Quaternary in Temperate and Tropical Areas /299 II. QUATERNARY AND PREHISTORY IN TEMPERATE AREAS: FOR EXAMPLE IN EUROPA 1. Chronostratigraphy, Climatology and Palaeoenvironment of Fossil Man : Generality The term Quaternary was created in 1829 by the geologist Jules Desnoyers, and once the first book concerning the Geology of Quaternary was published by Henri Reboul in 1883, a Quatemary era divided into two periods was accepted : the Pleistocene, which represents the entire period called ”glacial”, as opposed to the Holocene, which refers to the sub-present or “post-glacial” period. This new era was not only characterized by climatic variations connected with glaciation phenomena, but also, in Europe, by the appearance and development of prehistoric man. Study of the Quaternary applies the experience attained by geology, archaeozoology, anthropology and palaeobotany. The relative datations of the Quaternary are based on. the results of these different sciences: their correlation with methods of absolute datation contributes to better determining the chronological and palaeoclimatic table, which can be paralleled to that of the great phases of Prehistory (Fig. 20.1). Therefore, using data resulting from the multidisciplinary studies carried out in the geological, palaeontological or archaeological Quaternary deposits, we,’can try to reconstruct the environment of the sites that have, or not, kept man’s traces and to lay out our ancestors’ landscape during their walk through Europe for nearly two million years. As plant species are pdcularly sensitive to temperature variations and hygrometric changes, it is certainly palaeobotany that can most accurately verify climatic evolution, to which the landscapes, reconstructed out of spores, pollen grains, various macroremains (grains, fruit, bark, coals ...) and prints, are subjected. The Pleistocene is divided into three major parts, according to its climatic history, which has been reconstructed mainly in the light of palynological data. Indeed, we can observe that the chronological terminology of the different periods of the Quaternary bears most of the time on the denomination of eponymous geological or archaeological sites, which are real stratdgpes that have yielded pollen spectra of plant associations corresponding to precise climatic phases. Let us add rhat these major climatic phases have been defined by palynologists, as a function of the plant covers already established: - the “Glacials”, which are periods sufficiently long and cold for the whole forest vegetation to disappear and be replaced by a stratum o€ steppe Herbaceae; - the “Interglacials”, which are not humid climatic periods contributing to completely restoring arboreal vegetation; * I 300 / Current Concepts in Pollen-Spore and Biopollution Research I 2 3 4 5 6 7 8 9 10 li I2 l3 I4 l5 16 17 18 E"II0NIF.N Fig. 20.1 : Quaternary and Prehistory in Europa (after J. Renault-Miskovsky). - the "Stadials",which represent the cold periods of the glacial phases, interrupted by "interstadials", which are minor climatic oscillations that entail partial and botanically incomplete takeover of steppe by forest. 2. Change Over Pliocene-lower, Pleistocene and Lower Pleistocene The climatic history of the early Quaternary is indissociable from that one of the upper Pliocene, which was determined in Holland by Zagwijn (1963, 1974), as pollen analysis of the-clay deposits in Reuver and Tegelen has enabled three climatic phases to be distinguished: the Reuverian, the pre-Tiglian and the Tiglian (Fig. 20.2). Such a history of plants in the late Tertiary was also reconstructed in Italy through pollen analysis of Leffe clays (Lona, 1950). Y Palynology ofthe Quaternary in Temperate and Tropical Areas/301 In France, the latest palynological works on this climatic tuming- point are concerned with the Mediterranean Basin (Suc, 1980), Normandy (Clet-Pellerin, 1983), the Massif Central (Brun, 1971; Ablin, 1985) and the Bresse region (Farjanel, 1985). A correlation between the different climatic events that affected the Mediterranean Plio-Pleistocene from southern France to southern Italy has just been determined by Combourieu-Nebout (1987). 3. The Lower Pleistocene The Lower Pleistocene, which represents a still unsteady climatic period, from the late Pliocene to the progressive settling of the first glacial colds, has lasted from 1,800,000 to 700,000 years. The climate, at first temperate-hot and humid (north-European Tiglian), degraded during the first major climatic pejoration, materialized by an advance of the alpine moraines of the “GÜd$” In Europe, the thermophil flora took refuge in sheltered areas, but tQe slightest improvements