Quaternary geology of the central amazonian lowland area

Abstract

Occurrence and distribution of plants and animaIs are explained iri many parts of the world by climatological changes and by changing sea-Ievels during the Pleistocene.Large parts of the world's continental surface were reshaped during that time.Nqrthem Eurasia and North America are characterized by landscapes resulting from glacial activity during the Pleistocene.Sediments along more than 10000 km of the world' s coastal and island areas were deposited during the last sea-Ievel rise.In North America and northem Europe, pollen analyses of peat bogs, lake sediments, together with 14Cdating and radio isotope analyses contribute important information for understanding the geologial and climatological history of the Quaternary.Details of plant migrations are known and paleotemperature curves have been drawn.Considering the excellent knowledge of temperate Quatemary geology, surprisingly little is known about the tropicallowlands during this period of the earth's history.SERVANT et aI. (1993) have given a summary of Quatemary studies in eastern equatorial Africa and of South America which shows that only four study areas are situated in Central Amazonian Lowlands.The problem of the climatological history of Central Amazon basin is focused to the circumstances that some workers assume an arid to semiarid climate during the Pleistocene cold periods (e.g., DAMUTH & FAIRBRIDGE, 1970), while others do not find any proof of climatic changes (IRION, 1982).The main difficulty is that suitable deposits for studying Pleistocene history do not occur or are difficult to found in Central Amazon lowlands.This is in contrast to the well developed sediments found at higher latitudes, in particular glacial deposits, lake sediments, or organic deposits dating back to Pleistocene cold periods.