Wiek utworów formacji poznańskiej rejonu Poznania

Near Poznań, along Warta river valley; erosion process resulted in , the deposits of so called Poznań Formation forming outcrops or are coverd with a relatively thin Quaternary overburden. During routine geological and geotechnical soil testing, in years 1990–2004 carried out in downtownPoznań, in a number of locations organic soils were found in the top part of the poznań clay series. Samples of the organic soil were taken for further testing. One profile (no 8) and samples from other bore holes were palynologically elaborated. Spectra are characterized by the predominance taxa of riparian forest: Alnus, Ulmus, Celtis. Pterocarya. More arid areas were occupied by mesophylous mixed forest with Betula, Fagus, Quercus, Carpinus and shares of conifers, mainly Pinus. The role of swamp-forest with Taxodiaceae-Cupressaceae, Nyssa, Liquidambar, Myrica, typical for Miocene, is not important. Amount of herbaceous plants (except ferns) is low. The pollen of the plants of the temperate climate prevail, whereas thermofilous element is scarce. Age of these deposits was determined as the uppermost Miocene or Mio-Pliocene.