Late Cainozoic History of Vegetation, Fire, Lake Levels and Climate, at Lake George, New South Wales, Australia

摘要: The results of pollen, spore, algal and charcoal particle analyses from an 18 m core sample, dating ca. 730 000-0 a before present (B.P.), Lake George are described along with account five year study modern pollen-rain the same site. Also, pollen two isolated samples, about 4-7 Ma B.P., in separate location reported for comparison. sedimentary sequence is dated by means magnetostratigraphy radiocarbon. microfossil record provides longest relatively continuous Quaternary continental yet available Australia may document one world's combined vegetation, bush-fires, lake levels climates together accompanying plant migrations, redistributions extinctions. It so far only chronologically secure Late Cainozoic palynological database that spans entire Brunhes Chron. altitudinal shifts vegetation belts inferred suggest significant past changes terrestrial temperatures order glacial-interglacial cycles. revealed upper treeline was depressed 1200-1500 300-600 m, respectively, during glacial maxima cool-temperate intervals, reverted interglacials. Assuming average lapse rate 0.7 $^\circ$ C per 100 drop mean temperature warmest month (January) respect to periods respectively have been 8-10 2-4 C. A series eight cycles (phases I-XIX) recognized Chron at broadly corresponding stages 1-19 deep sea $^{18}$ O palaeotemperature record. correlation between former presented more section, 350 view resolve precipitation changes. considerably lower than prevailed maxima. Conversely, higher occurred some considerable lengths time In general terms, increased both interglacials interstadials evidence indicates Eucalyptus- dominated, dry sclerophyll (low, open) forests, now growing catchment, probably elsewhere southeastern result comparatively recent development. shown 'fire-sensitive' Casuarina-dominated several equally or rainforest taxa, dominated least half million years all but last 'fire-tolerant', Eucalyptus-dominated forests started expand onwards interglacial, 130 000 ago, conjunction large increases amount sediment. Since then, not did remain generally high level overall dominance open, eucalypt forest maintained throughout warmer except interstadial interval (zone D) glacial. Casuarina (under 23 $\mu$ type) as well taxa declined end finally disappeared catchment Holocene, culminating total extinction type under few hundred years. Some flora were undoubtedly long-term climatic change most appear precipitated through fire-frequencies (with maximum impact occurring 10 years), on bush-firing activities early man Australia. This presupposes presence Aboriginal people 90 earlier oldest archaeological human occupation Australian continent, proposition remains be tested future investigations. biogeographical studies reveal number Gondwanic commonly seen late Tertiary Australia, survived into Pleistocene George.