Szekessy Vilmos (szerk.): A Magyar Természettudományi Múzeum évkönyve 57. (Budapest 1965)

Csalogovits, I. J.: Geological and petrological conditions of the Szanda - Bercel area

Fig. 1.: Geological map of the Szanda-Bercel Area. Legends: 1. Holocene. 2. Pleistocene (Loess). 3.Hydrothermal veins and dikes. 4. Contact formations. 5. Bladder andésite. 6. Andésite decomposed hydrothermally. 7. Andésite. 8. Burdigalian gravel and sand. 9. Chattian brackish formation. 10 Chattian marine formation It is characteristic of the series that in the „schlier faciès" of the lower, typically marine sediments, a high degree of diversity appears both in level and regional spread. The thickness of sand banks varies, they occasionally show gradual transition toward the clayey layers, but sudden granulometric changes indicating erosive surfaces are also frequent. The sand banks are of tapering character. But the tendency dominating upward in the rhytmically changing sediment series proceeds clearly toward a gradually coarsening sediment and slow freshening of water. The lower levels are more clayey as a rule, while the lyditic gravel banks, more and more frequent in the upper levels of the series, indicate, in addition to the rhytmical fluctuations, the steadily approaching base of erosion. Glauconitic sand-stone, characteristic of the Chattian series of the Salgótarján basin, was not found here: but the other characteristic formation of the marine sediment, sand containing Pectunculus obovatus, occurs in a cellar at the northern end of Bercel village, north of the Bercel— Bér road. Freshening of water, taking place parallel with the appearance of the gravel material, is proved by the en-masse occurence of Tympanotonos margaritaceus in the gravel banks of the Becske sand pit.