The aim of this excursion is to examine new work on the eruptive and magmatic histories of Tongariro and Ruapehu Volcanoes. By integrating geochemical and isotopic analyses within a well-constrained framework of geochronology and volcanic stratigraphy, our studies have shown that growth of these andesite cone volcanoes involves multiple small batches of magma whose compositions are strongly modified in complex, probably polybaric plumbing systems on time scales as short as a year. Rapid production and ascent of magma is a characteristic of the Quaternary history of both the silicic and andesitic portions of Taupo Volcanic Zone (TVZ). Central TVZ is dominated by two exceptionally active rhyolitic calderas, Okataina and Taupo, while the landscape of the southem TVZ is dominated by two highly active composite volcanoes, Tonga1iro and Ruapehu. There are strong similarities between Tongariro and Ruapehu (compare for example Hobden et al., 1999 with Gamble et al., 1999).