Healy, J.; Vucetich, C.G.; Pullar, W.A. 1964 Stratigraphy and chronology of Late Quaternary volcanic ash in Taupo, Rotorua, and Gisborne districts. Wellington: New Zealand Geological Survey. New Zealand Geological Survey bulletin 73. 88 p.
Abstract: Part 1. Dating of the younger volcanic eruptions of the Taupo region. A complete list of 14 C specimens associated with the volcanic ash deposits of the Taupo region is given with their age. The use of the 14 C method of dating volcanic events is discussed, and the results are shown to agree fairly well with the stated order of accuracy, but the possible existence of some local factors that may affect absolute ages is suggested. To assist in interpretation of the results, the beds of the Taupo Ash Sequence have been redescribed in more detail and renamed the Taupo Sub-group, for which a suggested subdivision into formations is proposed. Two, the Taupo Pumice and Waimihia Formation, are named, and the members of these and the intervening formations have been correlated in 19 standard columns. The stratigraphy of the Taupo Pumice at various other localities is described. The Arawa Group is proposed to include all the superficial volcanic ash of the volcanic and surrounding regions. An approximate chronology for the Taupo Sub-group is given, and the last great eruptions, which laid down the Taupo Pumice, took place about AD 130. (auth)
Part 2: Stratigraphy of Holocene ash in the Rotorua and Gisborne districts. The stratigraphy of the uppermost volcanic ash deposits between Rotorua and Gisborne is outlined, and their correlation is demonstrated with the aid of numerous measured sections. In addition their relation to some of the ash deposits of the Taupo district is established. In the Rotorua district, 19 members, beds and formations have been identified and 10 of these are traced into the Gisborne district. Three new formations are defined, others are redefined, and the character of each is briefly described. With minor exceptions they are the products of eruptions in the Rotorua district and are constituted as the Rotorua Sup-group of volcanic ash deposits. The eruptive centres are indicated approximately by a series of isopach maps. (auth)