Abstracts of Symposium 55 and some papers from other related Symposia.

Environmental and Climatic Implications of the Morphology of Recent and Paleosols from Loess Exposure at Basaharc, Hungary

Olga MOROZOVA, Research Institute for Soil Science and Agricultural Chemistry HAS, Hermann-Otto-Str. 15, H-1024 Budapest, Hungary.

Soils, being a product of the environment in which their formation takes place, contain information of the environment as in a "coded" form, that is their morphological features, as well in the form of direct evidences, that are residues of plants and animals. In spite of certain difficulties associated with their interpretation, morphological futures of soils (coded information) present a highly reliable source of information since they reflect the environmental impact and primarily the biogenic influences exerted on the soil over a long period of time with spatial and temporal reference to the formation of a particular soil while remains of plants and animals (e.g. pollen and bones) can be redeposited subsequently from other places. Paleosols contained in Loess on the territory of Hungary due to their unique manifestation in loess and good conservation are valuable and reliable materials for paleoenvironmental reconstruction.

The soils studied contained three paleosols directly superimposed on each other and the recent soil on the top of the exposure. The lowermost is called Basaharc Lower (BA) and the overlying soils are Basaharc Double (BD1 and BD2). Their age is 65-70 th years BP for BA and 40-45 th years BP for BD soil complex being part of the Upper Pleistocene sequence.

These soils are widespread and can be found in most representative Loess exposures in Hungary but as indicated by their name the Loess-Paleosol sequence at Basaharc, on the second terrace of the Danube (100 km N of Budapest), is the key exposures for this type of soils. The soils were investigated using traditional soil characterization (including particle analysis by Robinson's method, the carbonate content by Scheubler's method, humus analysis) and micromorphological techniques. An almost continuous sampling and the large size of the section (125x60 mm) allowed tracing along the complete profiles of the soils to be carried out.

The analysis of the soils enabled the following to be achieved:

• a determination of the basic processes shaping the morphological features of studied soils. In paleosoils they were carbonate migration in the profile of the soil, biogenic structure formation and accumulation of a considerable amount of humus; initial clay illuviation was observed only in the recent soil.
  
• a judgement to be made concerning the type of water regime, conditions of decomposition of organic matter, mineral composition of loess and soils, degree of weathering of minerals and their transformation and the conditions of pedogenesis. On the basic of above, conclusions were drawn on paleoenvironmental conditions (prevailing climate, vegetation and fauna) and also about the duration and the stages of pedogenesis paleosols.`

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