Flood deposits include flood debris and shells of molluscs. Such assemblages of dead remnants of molluscs are called thanatocoenoses. Shells may com from any locality anywhere in the upper river drainage, but you can get shells of some species, that can not be obtained easily.
Flood debris from the Danube river in Slovakia:
It may seem, that there are only valves of a freshwater bivalve Corbicula fluminea.
But after a closer look there are many gastropod shells too. The following species of gastropods can be recognized on the photo:
- Esperiana esperi – one oblong shell with dots in the right center
- Esperiana daudebartii acicularis – one oblong shell on the top
- Theodoxus fluviatilis – a small black shell with white dots in the center
- Theodoxus danubialis – larger striped shells with a flat apertural plain
- Lithoglyphus naticoides – white globular shells without the apertural plain
There are also bivalves:
- Corbicula fluminea – brown rounded ribbed valves
- Dreissena polymorpha – two triangular valves on the top
gastropods 