 Explosive quartz-dominated volcanism took place at the surface, creating the Bozen Quartz Porphyry, which is hundreds of meters thick in South Tyrol.Crustral extension combined with erosion to reduce the height of the Variscan mountains to only a few hundred meters above sea level.Embayments of the Tethys Ocean flooded the edge of the South Alpine and Austroalpine superunits, leaving fossil-rich limestones as well as salt and gypsum deposits.