Székessy V. szerk.: A Magyar Természettudományi Múzeum évkönyve 41. (Budapest 1948)
Szurovy, G.: Geological structure of the Southern part of the Great Hungarian Plain
northern edge of he Great Plain (1920—40) (5). In 1940 these measurements were extended to the so called „gas-region" east of the Tisza, where the small structure of Tótkomlós NW. of Mezőhegyes was surveyed. After this, in 1940—43, the gravity structures of Battonya, Ferencszállás and Sándorfalva were determined by means of the torsion balance. As a starting point the gravity value A g = 20,05 . 10—3c.g.s., found near Makó in 1908 by Oltay was chosen. These measurements were executed by the Royal Hung. Baron Roland Eötvös Institute under the direction of Mr. E. F ek e t e and Mr. E. Bassó. At the same time the „Seismos" Ltd., Hannover, was charged to survey the whole territory south of the line Dunaföldvár—Kecskemét—Körös river—Mezőtúr—Püspökladány—Kismarja—Nagyvárad. To speed this work up the „Gesellschaft für praktische Lagerstätten forschung", Berlin, was also called upon later to help and carried on its work in the Bácska. Both these contractors used the Thyssen—Bornemissza Gravimeter. The results obtained from torsion balance and from the gravimeter agree very,well. There are, it is true, some differences in the gravity values; but these are merely due to the fact that the torsion balance gives the values without the Bouguer correction. By these extensive works the gravity chart of the entire southern part of the Great Plain has been compiled (Fig. 1, 2). A total of 27 marked gravity maxima and 20 minima was found. The measurements have also been extended to the mountains at the rim of the Great Plain in order to make possible a better interpretation of the results. The more conspicuous gravity structures were then checked by seismic investigations. The seismic measurements comprised reflection and refraction methods, and were executed by the „Seismos" Ltd. Hannover, and by the „Gesellschaft für praktische Lagerstättenforschung", Berlin, with 12 seismograph apparatuses. In the velocity curves two marked velocities could be observed: viz. one of 3,500 m/sec and one of 6,000 m/sec. Moreover seismic measurements have confirmed the supposition that the gravity measurements give the gravity diagram of the basin's substructure. It could be gathered from the measurements-that most of the gravity maxima are to be interpreted as marked elevations of the base rock. Greater discrepancies, evidently caused by a difference in the specific gravity of the rocks, turned up in the structures Sándorfalva and Gyula only. Jn the reflexion profiles three well reflecting horizons could gene-