The Cenozoic platform (German: ) comprises Tertiary and Quaternary rocks. It is also known as the unconsolidated rock level because, due to their young age, the Cenozoic sedimentary rocks have often not experienced intensive diagenesis and are therefore often not cemented. Because the youngest deposits in an uplifted area are removed first, the Cenozoic platform deposits occur extensively only in young Cenozoic subsidence areas in the Central European Blocks region. The largest continuous outcrops are the Upper Rhine Graben with the Mainz Basin and the Molasse Basin (Alpine foreland trough). Special subsidence areas are the Nördlinger Ries and the Steinheim crater, both originating through a meteorite impact event. The Cenozoic deposits in the Central European Blocks region consist of both siliciclastic rocks and limestones and both marine and continental sediments. The Cenozoic in Germany is also represented by volcanic rocks. In contrast to the mostly acidic (SiO2-rich) volcanic rocks of the transition level, the Cenozoic formations are mostly intermediate to very SiO2-poor (trachyte, basalt, phonolite, tephrite, nephelinite and basanite). The largest Cenozoic volcanic areas in Germany are the Vogelsberg Mountains, the Westerwald, the Rhön Mountains and the Eifel.