For the sake of convenience Chatham Island may be divided into three portions—a northern, a central, and a southern. The northern portion consists of two peninsulas, the western and the eastern, which are separated from one another by the northern and widest portion of Te Whanga Lagoon, and are connected only by the very narrow strip of land which in the north separates the lagoon from the ocean.
The western peninsula—Whareka on the map (49)—is about 16 ½ miles in length from Te Raki Point to Waipapa on the lagoon, and some seven miles broad at its base from the north of Waitangi Beach to the shore near Wharekauri. In the north two triangular pieces of land jut out northwards, culminating in Capes Young and Pattisson respectively. The eastern peninsula is a narrow triangular piece of land nearly nine miles and a half in length and five miles in width at the base, its widest portion. The northern portion of the great lagoon is eight miles and three-quarters in width, and is separated from the ocean by a narrow strip of land varying from a mile and a quarter in its widest to one-eighth of a mile in its narrowest part. The central portion of the island is occupied for a great part of its area by the southern part of Te Whanga Lagoon. This is separated from Hanson Bay on the east by a very narrow strip of land, varying from a mile and a half to a quarter of a mile in width; but on the west the land bounded by Petre Bay is of greater size and importance, having a width in the south of from two and a half to three miles and in the centre a mile and a half, while in the north a broad triangular piece of land stretches into the lagoon, measuring seven miles and a quarter from Karewa to the Waitangi Beach.
The south portion of the island forms a compact four-sided block of an almost uniform length of nine miles and a half from Petre Bay to Pitt Strait, and with a breadth of, from east to west, 13¼ miles. The south-east corner beyond Ouenga juts out slightly towards the east.
The greatest length of the island as a whole is thirty miles, measuring from Cape Young to Te Rahui, and its greatest breadth, measuring in the north from Te Whakaru Island to Te Raki, is thirty-five miles. From the above it may be seen that, owing to the peculiar shape of the island, no place in the interior is at any great distance from the sea or the great lagoon: in the north two miles and a half is the extreme limit, in the centre only one and a third miles, and in the more compact south four miles and three-quarters. Hence, no part of the island is beyond the reach and influence of a strong sea-breeze.
Speaking generally, the surface of the land is low, though in most places more or less undulating. The southern portion of Chatham Island is by far the highest above sea-level, and in comparison with the rest of the island looks quite hilly. Its highest portion, however, the Trig. station near Te Awa-tapu, is only 286 m., and Pipitarawai, the highest point of the main ridge and watershed of that part of the island, is about 2 m. lower. From this ridge to the sea stretches a kind of tableland, culminating in some abrupt cliffs, which vary in height from 182 m. to 213 m., and are cut in places into deep gorges by the small streams which drain the tableland. From the other sides of the Pipitarawai Ridge the land slopes gradually downwards to the coast. The flat but usually undulating surface of the northern and central portions of the island is relieved here and there by conical hills, which reach at times a height of 152 m. or 182 m., and of which the most important are the forest-clad Korako, Wharekauri, and Maunganui. The extensive coast-line varies in character from flat ground bordered with sandhills or low rocks to the high cliffs of the south coast. Small streams are abundant all over the island, but only two, the Waitangi and the Awainanga, rise to the dignity of rivers. Most of the streams flow slowly, and the water is always dark-brown, from the large amount of peat which it holds in suspension. The great lagoon, Te Whanga, is nearly fifteen miles in length, and its area is estimated at 46,000 acres (18). In certain places the lagoon is so shallow that it can be forded on horseback; indeed, under certain conditions of the wind the northern ford may be quite dry. Besides Te Whanga there are many other lagoons and lakes; indeed, it is stated that fully one-third of the surface of the island is occupied by water (18). Bogs of considerable size are very frequent, and occur both on the high and low ground.
Thus both the very low north-west of the island and the highest parts of the tableland of the south consist of quaking bog. Even when the ground is not boggy its water-content is usually very considerable; and, speaking generally for the whole island, excepting in places long cultivated, wet ground is much more common than dry.
The soil in most parts of Chatham Island consists of peat, which must in many places be of a very great depth, Mr. Travers stating that it is often 50 ft. deep (51). If the peat through any reason should become dry it will burn with great readiness, and should it be set on fire it may slowly burn for many years. Such burning—and it is perhaps from this that he gave his estimate of the depth of peat—is thus described by Mr. Travers (51, p. 177): “In several parts of the island this peat has been on fire for years, burning at a considerable depth below the surface, which, when sufficiently undermined, caves in and is consumed. I have seen the loose ashes arising from these fires upwards of 30 ft. deep.” On the peaty plain on the north-west peninsula I saw a hollow caused by the peat having been burned, which even then was smouldering in places. This hollow was about 3 m. in depth—i.e., only one-third of the depth stated by Mr. Travers—and its area about 2 acres. The burning must have taken place many years ago, for the bottom of the hole was a dense mass of vegetation, thus affording a very interesting example of what species of indigenous plants will, under present climatic conditions, people a piece of virgin ground. Very often these burnt-out hollows become filled with water and remain as permanent lakes; indeed, Mr. A. Shand is of opinion that probably all the lakes of the island, including even those of the tableland, have originated recently in this manner. Besides peat, a much richer soil, called locally “red clay” and formed of disintegrated volcanic rock, occurs in some few places—much of the country from the south of Lake Huro to the Whanga Lagoon and for some distance further southeast is of this character; other patches occur from the Ngaio to Waitangi along the coast, and others again in the neighbourhood of some of the old volcanic conical hills.
As pointed out in the introduction, I did not visit quite a number of important localities. of these the chief were the extremity of the north-western peninsula, from Maunganui to Te Raki Point; the south coast of the north-western peninsula; the narrow slip of land along the north coast from Wharekauri to Matarakau; the east coast of the island from the ford over Te Whanga to Ouenga; and the greater part of the coast-line on the east from Waitangi to the Horns.