Nowadays there is a growing demand for rapid and accurate determination of grain size distribution. The conventional pipette method is time-consuming and provides less detailed data compared to recently introduced methods. However, in Hungarian practice the pipette method is still considered to be the standard one, as there are a long series of measurements, and grain size thresholds used in sedimentology and soil sciences are based on this approach. The aim of our research was to determine the comparability of the laser diffraction method (LDM) with the conventional pipette method (PM), in order to investigate the controversial question on the interchangeability of the two methods. Based on our measurements on some representative fluvial sediment samples, we found that the largest difference in results can be expected in the silty grain size range. However if the main fractions (clay, silt, sand) are considered the methods provided similar very results, and correlation factors were above 0.92. In all, the LDM has a clear advantage because of its speed, reproducibility and fewer possibilities for operator failure.

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Freshwater carbonate deposit, as a special phenomenon in the Danube-Tisza Interfluve, located in the centre of Hungary, is a significant geological heritage in the Carpathian Basin. At present there is not any applicable method to investigate the presence of carbonate layers in an undisturbed way, as neither vegetation nor morphological characteristics indicate unambiguously these formations. Ground-penetrating radar technology is widely used in various earth science related researc hes, and the number of applications is steadily increasing. The aim of the study was to determine the spatial extension of freshwater limestone using geophysical methods near Lake Kolon, Hungary. The lake, which is now a protected wetland area with opened water surfaces, was formed in the paleo-channel of the River Danube. Measurements were performed with the help of ground-penetrating radar, the results were calibrated by high spatial resolution drillings. Investigations have been made since 2012, and freshwater limestone was detected at seve ral locations determining the more exact extension of the formation. Ground-penetrating radar proved to be an appropriate method to detect the compact and fragmented freshwater limestone layers in such an environment. However, based on the results the method can be best applied under dry soil or sediment conditions while the uncertainty of the results increases significantly as a matter of higher soil moisture. Further control measurements are necessary verified by several drillings in order to give an exact method to determine freshwater limestone.

A complex geomorphological research was car-ried out on an aeolian sand dune in Inner Somogy, Hungary. Sedimentological analysis showed three layers of sediment composed of sand with differing characteristics (Györgyövics et al., 2014) which suggested at least 3 aeolian phases in the region. OSL dating of samples from the same boreholes con-firmed these periods and determined that sand was deposited during the Late Glacial, the Dryases and Boreal phase (Kiss et al. 2012). However, carrying out a GPR survey revealed much more detailed structure of the particular dune. Compar-ing research results and applying GPR profiling in the early stages of geomorphological investigation could help choos-ing the OSL sampling points and depths resulting in a more precise study.