A Móra Ferenc Múzeum Évkönyve, 1971. 1. (Szeged, 1971)

Molnár, Béla–Mucsi, Mihály–Magyar, László: Latest quaternary history of the southern stretch of the Tisza valley

A Móra Ferenc Múzeum Evkönyve 1971/1 LATEST QUATERNARY HISTORY OF THE SOUTHERN STRETCH OF THE TISZA VALLEY by BÉLA MOLNÁR—MIHÁLY MUCSI—LÁSZLÓ MAGYAR (Szeged, Geological Institute of University) Summary: The possibilities for the discrimination of Pleistocene and Holocene sediments of different faciès and their geological history in the alluvial area of the southern Tisza valley are shown by the use of various lithological methods. During the detailed investigations and geological surveying of the Quaternary sediments of the Great Hungarian Plain, a research programme launched in 1950 by the Hungarian Geological Institute, several monographs were published on this subject (I. Miháltz 1953, J. Siimeghy 1953). The results of part- researches, however, have been published just in a very small number, despite the great help they may provide for the better understanding and the geological reambulation of single areas (T. Ungar 1956). In his paper „The hydrology of the southern part of the Tisza valley" I. Miháltz (1966) already dealt with the near-surface sediments of the vicinity of Szeged during the preliminary geological investigations connected with the Szeged Barrage Project. In the present paper his conclusions have been adopted extensively as a basis to rely upon. I. Miháltz considers the southern Tisza valley to comprise the old flood-plain of 20 to 30 km width to the south of Csongrád. According to him, the Tisza valley can be split up into two parts. The Tisza valley s. str. comprises the Holocene erosioncarved depressions of the river and the zone filled up by its alluvium. The Tisza valley s. 1. consists of the deep-seated zone of the valley filled up by Pleistocene detrital material, of the margin of the Danube-Tisza Interfiuve and of the part of the TransTisza Region sloping towards the river. The southern part of the southern Tisza valley is accordingly rather well known, while its northern one is not, even though the understanding of the geohistorical evolution of the Tisza valley would require the proper knowledge of this part, too. Therefore, large-scale geological surveying was carried out in the norther part of the valley. The agriculturally cultivated alluvial area has been feeling an urgent need for the introduction of farming under irrigation, requiring to dig new canals. A continuously increasing number of industries have been located on alluvial soils along the banks of the Tisza. These facts also justify the more detailed geological investigations of the Tisza alluvium. The area of larger-scale investigations has been selected to the east of Pusztaszer village in the northern part of the southern Tisza valley, at the junction of the Danube-Tisza Interfiuve and the Tisza valley. (Fig. 1). In the west the Tisza valley is bounded by the Danube-Tisza Interfiuve Ridge. The Ridge is constituted in a thickness of 20 to 150 m by Pleistocene eolian sedi5