The locality of Maršovický Hill (N Bohemia, Czech Republic) yielded an example of a Cretaceous sea-bottom composed of Nametarhyolite. Two types of trace fossils penetrate the substrate, namely Thalassinoides isp. and ?Gastrochaenolites isp. Thalassinoides originated presumably in a firmground, i.e. the metavolcanite had to be "delithified" in some patches and subsequently re-hardened again. ?Gastrochaenolites isp. is interpreted as a boring trace of decapods.