Page:Transactions NZ Institute Volume 9.djvu/619

572 another patch of limestone, containing the usual fossils, and dipping to the west at about 10°, whilst at Te Tuhi a few large blocks are left capping the hill, also with the same fossils. It will be seen from an inspection of Section 3, Plate XXIII., that if the limestone there shown were continued westwards with the same dip, that it would cut the Maungaharuru Range, both at its highest point, 4,265 feet above the sea, and also at Te Waka, in the positions where we actually find it capping the range. This shows, I think, that the introvening space was at one time occupied by continuous sheets of limestones, which would have rested unconformably on the lower strata of conglomerate, etc., and which have been denuded off; in the first place by the action of the sea as the country generally rose, and later by sub-ærial agencies.

I have mentioned above the occurrence of pumice in this district. It is found nearly everywhere: on the river terraces, the hill sides, and on top of the highest mountains, covering the surface with a deposit of sand more or less deep, and in larger or smaller particles. During the course of the last five years it has been my duty to visit the tops of most of the higher mountains lying between Napier and Tongariro, and thence northward to the country under consideration, and in every case a deposit of pumice sand has been found, sometimes plainly showing, at others covered by vegetation. On the Panikiri and neighbouring ranges around Waikaremoana, it is found of a considerable thickness, whilst the lower lands along the lake are covered by it sometimes to a depth of three feet. On the eastern side of the Maungaharuru Range it is very thickly deposited, being often, in the gullies, six to eight feet thick. The extensive terraces of the Lower Mohaka River (which contain as large a quantity of level land as is to be found in the district) are thickly covered with it, thereby rendering them unfit for cultivation.

Towards the east the deposit gradually thins out, until, approaching the vicinity of Poverty Bay, very little is seen. The only spots that are free from it are the lowest terraces of the rivers and the surface of the slips, and, as the country lying along the coast is the most subject to these slips as mentioned above, it is here that the pumice has in a great measure disappeared, thus allowing the grasses to spread.

The general opinion appears to be that this pumice was ejected from Tongariro and the adjacent volcanoes, and was spread over the surface of the country by the wind; and there are certain considerations which favour this view, such for instance as finding the greatest thickness of the sand on the lee sides of the high ranges, where it would naturally accumulate; and also from the fact that the size of the articles appears to diminish as we recede from the supposed centre of distribution; but at the same time this will not account for all the facts. An examination of the sand seems to show that