In considering the geological features of the region of Lake Taupo, it may be imagined here, as in other cases, that the primary volcanic eruptions were submarine, and that when first that portion of New Zealand now known as the North Island appeared above the surrounding sea, forced upwards by some volcanic freak of nature, the Taupo table-land rose perhaps rapidly, perhaps by slow degrees, to its greatest elevation. The volcanic eruptions which produced this phenomenon may, in short, have been instantaneous or slow in their action; but be that as it may, their work has been indelibly impressed upon the face of Nature in a way which has caused its wonderful results to last through vast periods of time. The volcanic agencies, however, did not rest here. The Plutonic fires, still active in the interior of the earth, burst through the elevated plane, and caused big mountains to rise up in the form of serrated ridges and truncated cones, which poured out their streams of lava and other kindred products over the surrounding country. Hence dotted along the Taupo volcanic zone are stupendous mountain ranges and graceful trachytic cones standing alone or rising from amidst a cluster of minor elevations to heights which vary from 1200 to nearly 10,000 feet above the level of the sea. Of the former class the most extensive are the Kaimanawa mountains and the kindred systems, with the Tuhua ranges and the wooded heights of Hauhungaroa and Hurakia, while the cone formation is exemplified in the grandest proportions in Ruapehu, Tongariro, Pihanga, Tauhara, Kakaramea, Kuharua, Puke kai-kiore, Karangahape, Haurungatahi, Hikurangi, Hurakia, and Titiraupenga, all of which indicate various centres of volcanic action.