Geology and Geomorphology
The majority of the Třeboň Basin PLA/BR comprises the Třeboňská pánev Basin geomorphological unit and in the eastern section on a crystallinite basement, the elevations of the Kardašova Řečice hilly country.
The basin, of tectonic origin, is filled with Mesozoic and Tertiary sediments belonging to the shallow water fluvio-lacustrine sediment type. These formed as kaolinized minerals were carried from the raised margins into the basin area. The dominant sediments are from the Mesozoic period (Upper Cretaceous epoch). Over a much smaller area, especially to the west of the PLA/BR, the sediments are only of Tertiary origin. From the Quaternary sediments, the most widespread is the Pleistocene accumulations of fluvial sand and gravel (including feldspathic sands) on the alluvial plains of the Lužnice and Nežárka rivers, which are up to 30 metres thick. Holocene sediments are represented by the youngest layers of fluvial sand and gravel, floodplain and slope loams, fishpond sediments, acidic fens, and oligotrophic peat. The most significant environment type, from a nature protection point of view, are the air-blown sands, which probably originate from the end of the last glacial period.