Matthias van der Hallen

The #EuroRoad23 championships give us the opportunity to introduce the geologically most puzzling mountain of Europe: the @ColDuVAMdrenthe! The Dutch province of Drenthe is world-famous for Pleistocene ice-age geology. It is scattered with large ice age erratics: enormous blocks of gneiss and granite that were transported from Sweden and Finland by giant glaciers (check out @Hunebedcentrum). Those glaciers also bulldozered sand and gravel into hills, but the sediments that make the Col du VAM clearly 'unconformably' overlie the ice age deposits and must therefore be younger! Geologically, the Col du VAM deposits are best described as a sedimentary mélange, a poorly sorted, polymict (i.e., with elements of varied composition) and poorly stratified (i.e., layered) agglomerate. It is rich in plasticite, contains iron accretions and abundant bituminous (i.e., organic material-rich) clasts, and may contain elevated heavy metal traces. There are plenty of ichnofossils (i.e., fossil footsteps) of giant caterpillars. There is no proper geological definition of the sediment association of the VAM subsurface, but among some geologists it is casually referred to as piloshite. Piloshite is an excellent material to explain 'critical taper theory' to students. Critical taper is the equilibrium angle of a wedge-shaped agglomeration of material that is bulldozed up (tectonically or otherwise). That angle depends among others on material properties, but piloshite makes slopes of up to 16%! So this year's European Champions will have to dig deep for their wins. But we advise not to dig too deep... @UUEarthSciences @UUGeo @UniUtrecht @Naturalis_Sci @museumnaturalis