Als de wind vrij spel heeft… Ichnofossielen in mioceen zilverzand van Heerlerheide en nóg een vuursteenzwerfsteentje

A fairly rich assemblage of ichnofossil taxa, predominantly Ophiomorpha nodosa Lundgren, 1891 (produced by decapod crustaceans), is recorded from the late Early to early Middle Miocene Heksenberg Member (Breda Formation), as exposed at the Beaujean sandpit at Heerenweg (Palemig, the Netherlands). These ichnofossil suites occur in a light brown to greyish level and are best seen on wind-blown surfaces in the now abandoned, north-eastern corner of the sandpit, around 3 to 4 metres above the present working level. Just above this level, within the pure sands, a small flint pebble of Late Cretaceous age and presumably local origin was found. As a result of dissolution, the sands (‘zilverzand’ in Dutch) of the Heksenberg Member do not retain any calcareous material; no molluscan shells or decapod crustacean remains are known. Lignite seams (Morken and Frimmersdorf) allow the Beaujean section to be correlated with the Ville Formation in nearby Germany (Lower Rhine area).