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JoEG Volume 4 (2011)
The structure and origin of loess dolls – a case study from the loess-paleosoil sequence of Sütto", Hungary
Abstract:The research of secondary carbonates from loess-paleosoil sequences focuses not just on the micro-scale types, but as well on the macro-scale ones. Loess dolls or concretions belong to this last category. Concretions are found frequently under the paleosoil levels referring to a very probable connection with leaching processes and precipitation from carbonate-rich solutions. Research was carried out on the loess-paleosoil sequence of Sütto", Hungary. The methods used in this work were the morphological description of concretions, the analysis of the structure after cutting into two or more parts and treatment with 10% hydrochloric acid. Altogether 29 samples were analysed from the sandy loess layers between the depth of 0.65–5.55 m and 12.70–14.75 m. Based on the results three main types concerning the inner structure of the concretions were determined: a.) concretions with longitudinal and/or perpendicular cracks; b.) concretions containing one or more condensation nucleus; c.) the combination of the above listed proper-ties. From these different structures more conclusions could be drawn on the origin of loess dolls. The carbonate precipitation could have taken place in or around cavity systems of biogenic origin (as root-related channels or features, and biogalleries) and of non-biogenic origin (because of the structural properties of the sediment). As precipi-tation nuclei the cementation of hypocoatings played an important role as well. A multiphase development history of the loess dolls were in many cases characteristic.Manuscript:Discharge calculation of paleochannels on the alluvial fan of the Maros river, Hungary
Abstract:The aim of the study was to identify the abandoned channels on the alluvial fan of the Maros River and to calculate their paleodischarge. As the first step of the investigation regional equations had to be made for discharge calculations based on the earliest available discharge data for the rivers of the Tisza catchment in Hungary. Equations between discharge and channel parameters were created with high correlation coefficient. Then the paleochannels were identified on the Hungarian part of the alluvial fan. The paleochannel generations are located in continuous zones with well defined boundaries. The density of the abandoned channels varies on the alluvial fan, as some areas densely covered by channels and on other areas almost free of paleochannels. Braided, meandering and misfit channels were separated, but only the morphometry of the meandering and misfit channels were measured (width, ratio of curvature, half-wavelength and cord-length). Based on these morphometric parameters and the discharge equations the mean discharge of the channels was calculated. The greatest discharge was around 6300 m3/s while the smallest was 31 m3/s. However, several abandoned meandering channels had slightly greater bankfull discharge (700-900 m3/s) as the present-day Maros River.Manuscript:Quantifying the geodiversity of a study area in the Great Hungarian Plain
Abstract:Geodiversity is understood as the diversity of the abiotic nature. It expresses the variety of stones, minerals, fossils, places, landforms, processes, soils and elements of hydrology. As geodiversity assessment is a rather new research area, the number of publications concerning geodiversity is growing fast. In this paper we quantified the geodiversi-ty of a study area located at the Danube-Tisza Interfluve in the Great Hungarian Plain using the method worked out by Hjort and Luoto (2010). We wanted to know how the diversity varies in space at low-land areas applying different indexes. Geodiversity was represented by three different indexes. Total geodiversity was calculated by summariz-ing the geologic features, the landforms and the elements of hydrology found in each unit. Then we grouped the landforms by the (exogenic) processes which formed them, and the number of these processes gave the value of the geomorphologic process diversity. Finally we calculat-ed the geodiversity index by Serrano-Canadas and Ruiz-Flano (2007). The absolutely homogenous units (totally waterlogged areas and the flat sand sheets) have the lowest geodiversity. It is higher at the border of the sandy, peaty and waterlogged areas. At this lowland area there is no relationship between the geodiversity and the relief. This is the first work applying this method in Hungary, so the results are yet not com-parable.Manuscript:Geomorphological and stratigraphic analyses at the archaeological excavation in the Megapark, Nyíregyháza-Oros
Abstract:The aim of our morphological and stratigraphic investigations at the archaeological excavation in the area of the Megapark at Nyíregyháza–Oros is to make the reconstruction of the Aeolian development of the study area more accurate. The excavation is located between the rem-nants of two abandoned river beds in a wind-blown sand area near the crossing of main roads 4 and 41 East of Nyíregyháza–Oros. Eight bore-holes were drilled in the site of the excavation. The cores were sampled in order to perform the sedimentological analysis of the penetrated strata. Strata of the sand dune are divided by a fossil soil horizon in which a cemetery from the age of the Hungarian conquest was found. Underneath the cemetery findings from the imperial age and urn graves from the Bronze Age were excavated. This suggests that wind-blown sand covered the soil horizon in a thickness of 1-1.5 m by the age of the conquest. The 3-4 m thick wind-blown sand excavated from the findings indicates sand accumulation following the 10th century.Manuscript:
