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Gravels exploited from the gravel pit in Trstenik area, in the Sava River floodplain SE from Zagreb, are variegated and of complex composition. All together 1399 clasts from the bulk (gross sample) and 606 from the fraction >32 mm were measured (x, y and z axes) and their lithology, shape and roundness were carefully studied. Numerical analyses were done through the Microsoft Excel program. The Zingg-shape analyses and flatness calculations were also applied. Gravels proved to be polymictic, composed of carbonate, clastic, igneous and metamorphic rocks. Size of measured clasts in bulk sample varies from 6.8 till 110.25 mm along the longest axis (x) and such value exhibits normal distribution. Carbonate, well rounded, disc-shaped clasts prevail. Sporadically, cross sections of red and green algae and macrofossils are visible on pebble surfaces, enabling the determination of stratigraphic age of some pebbles/source rocks. The second abundant group is composed of variegated sandstones, of red, green, grey, brown and yellow colour. Coarse-grained clastic rocks form less rounded clasts, similarly as green diabases. Angular quartz and chert clasts appear in all fractions, but they are more common among small-sized clasts. Modal composition, size and shape point to the important transport route from the Medvednica Mt., by combination of glacial, alluvial and lacustrine processes.

gravels; lithology; size; shape; Sava River; Croatia