Vulcanicity and vegetation in the Rotorua district: Geology of the Rotorua district

[First paragraph...]
The Rotorua district is 3500 square miles in area, extending north from Maroa and Murupara to the Bay of Plenty coast between Matata and Tauranga. The Taupo Volcanic Zone, which lies as a belt northeast from Ruapehu to White Island, passes through the centre of the area. In this account the rocks have been divided into a number of groups on a lithologic basis, and their distribution and approximate age range are shown in Figure 1. These groups do not include late Quaternary volcanic ash, which mantles the entire area superficially and in places is more than 40 ft thick.