Guide of B.-A.-Z. county

The subsided area at the mouth of the River Sajó formed at the beginning of Pleistocene (about 2,5 million years ago) was the place for alluvial depositing carried by the rivers ancient Sajó, Hernád, Bódva until 11-12.000 years ago. This alluvium is the most perfect one on the Great Hungarian Plain. The total amount of settled gravel and sand comes to about 125 km2. The spatial order of sediments features a growing refinement from the north to the south. According to F. Franyó (1966) he total thickness of the Pleistocene-age gravel layers (so called Sajó-gravel) can get up to 40-60meters at the area concerned. Its subsurface depth is little, between 3-5 meters. The composition of accumulated sediment is mostly metamorphic (80-85% of it is quartz), its significant part has been accumulated several times. The carbonite and andesite gravel components eroded from the sedimental-area in front of the foot of the Mount Bükk mix to this accumulation only in small percentage. That is the reason for the wide-range usage.
The local cuttings forming at the end of the era were followed by drying out, and at some places the surface-forming effect of the wind. During the period after the gravel-accumulation muddy-clayey depositions formed on the grave-silt.