Székessy V. szerk.: A Magyar Természettudományi Múzeum évkönyve 41. (Budapest 1948)
Szurovy, G.: Geological structure of the Southern part of the Great Hungarian Plain
mainland. In the Oligocene and Miocene periods again a depression followed which reached its maximum between Upper- and Lower Mediterranian. During this period several transgressions and regressions alternated. The transgressions were connected with orogenic phases and the regressions with sedimentation. The second sinking of the Great Plain was not uniform. Thus the older Miocene- and Paleocene sea did not overflow the whole region, but only formed broad channels along the line Budapest—Miskolc—Eperjes and gulfs in the region of the present districts of Békés and Csanád. In the Upper Mediterrane the whole region was then uniformly inundated. In the Upper Pliocene the territory became again a uniform continent. After the Levantiian the brooks and rivers formed fresh water ponds and swamps (3). In consequence of the supposition that amongst the Tertiary sediments there might also be liydrocarbonous deposits — (in very many Artesian water wells smaller amounts of marsh gas and methane have been found) — the Hungarian Fisc drilled several deep wells the geplogical results of which are compiled in table No. 1. As regards hydrocarbons these wells cannot be said to have been very successful (4). Besides unimportant traces of oil and asphalt, only in the following wells more considerable amounts of gas have been found: Hajdúszoboszló 1 130.647 eu ft/day Total: 577.741 eu ft/day. The gas consists of 98 per cent methane and can only be exploited together with great quantities of water. The well Baja 1., also mentioned in table I, wras sunk by the Anglo-Persian Oil Co., and the well Tiszakürt 1. by the Hungarian American Oil Industry Co. by order of the State. III. Geophysical Preparatory Work. Torsion Balance Measurements. The earlier torsion balance measurements were limited to the region of Makó—Arad (1908—09) and to the region of Baja—Kecskemét—Debrecen—Hajdúszoboszló and some smaller districts on the Hajdúszoboszló 2 116.523 „ Karcag 1 141.522 Karcag 2 38.982 Debrecen 1 + 2. 150.067