The Collaborative International Dictionary of English v.0.48:
Flysch \Flysch\ (fl[=e]sh), n. [A Swiss word, fr. G. fliessen to flow, melt.] (Geol.) A name given to the series of sandstones and schists overlying the true nummulitic formation in the Alps, and included in the Eocene Tertiary. [1913 Webster]