Székessy V. szerk.: A Magyar Természettudományi Múzeum évkönyve 41. (Budapest 1948)
Szurovy, G.: Geological structure of the Southern part of the Great Hungarian Plain
lignite, and frequently thinner or thicker continuous beds of lignite may be found. The stepped fracture of the strata is striking. In the upper part of the lower Pannoné we still find rather limy middle gray beds of shaley marl with thick intercalations of fine sand or thinner ones of sandstone. In the lower parts of the lower Pannoné these beds change to a compact dark gray marly clay, the upper part of which is rather uniform, compact, hard, and well stratified. Its lower part contains several thick beds of a friable light gray fine sandstone. In the lower Pannonian no more lignite beds are found; onlv carbonized remainders of plants are abundant (Fig. 3). It is remarkable that in the northern wells (Körösszegapáti, Kismarja) the sandstone layers are rather unimportant and less developed than in the southern wells (Tótkomlós, Tiszakürt, Ferencszállás, Sándorfava) (Fig. 4—5). The density of the marly clay is constantly increasing with the depth, is characterized by a conchoidal fracture and finally changes to a browny gray calcareous marly stone, which is interlaced with thin fissures. The fissures are often filled with milk-white calcite veinlets, and pyritic concretions are frequently found. The whole series from Holocene to the bottom of the lower Pannonian is rather sandy. It may well be maintained that above the lower Pannonian the sand is predominant. The sands of the Holocene. Pleistocene and Levantiian alternately consist of finer or coarser quartz grains. Now and then they change to fine gravel. The sands of the Upper Pannonian are fine grained and very micaceous. The lower Pannonian sandstones mainly consist of fine grained to middle grained quartz with a little less mica. In the Lower Pannonian marly clay the embedments of finest sandy mica films are very typical. In the deep drillings a manifold basement has been pierced, namely; crystalline schists, shale, dolomite, breccia of dolomite and limestone, and conglomerate. The crystalline schist belongs to the paragneiss group; it is very amphybolitic and shows strong metalliferous traces. The shale is rather soft, almost clay. Its colour is a dark gray; it is very light of weight wavy and folded. The dolomite lias a crystalline structure; it is brownish gray and contains many dark gray chert noddles and is full of fissures. In the fissures well developed druses of calcite and dolomite crystals. The breccia is rather a change to conglomerate, as it consists of larger boulders of dolo-