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enormous zone of plutonic rocks, which in our province are mostly concealed below the sea, but are highly developed towards the north.

The data in this section dip and strike are all from actual survey as far as to the central part of Mount Cook, and a collection of rocks made for me at the west coast, near the base of Mount Cook, by Mr. James Mackay, Assistant Native Secretary, has enabled me to supply the deficiency in the direct observations.

The rocks occupying the western side, are in fact true metamorphic rocks, gneiss, mica, chlorite, graphite slates, etc., together with some quartzites, semi-crystalline sand stones and foliated flagstones. No granite or other plutonic rocks seem to occur there, as Mr. Mackay, an acute observer, was not able to find a single specimen of them. We may therefore assume that the hypogene rocks by which the Alps have been upheaved to their present position, and which are found so extensively in the Nelson Province, have partly been denuded, or lie concealed under tertiary or secondary strata.

The rocks which form the central chain are of so varied a nature or character, that it is almost impossible to give a full description in a report of this nature. Clayslates, gray wacke slates, and shales, alternate sharply with sandstones, flagstones, conglomerates, or pebble beds, or they merge into each other, or die out. Generally the strata, the strike of which may be said to be from north-east to south-west, stand vertical or nearly so, a dip of 75 deg. to 80 deg. being the average.

Their strike is generally regular, and they show a continuity of huge and steep foldings. In few places only greater disturbances occur, where the strata have not only been bent, but also contorted, faulted, and thrown over in various directions.

Of this I observed some very interesting and instructive instances, particularly in the northern main branch of the Rangitata. Some continuous faults also occur, the principal ones which fell under my observation were near the source of the River Havelock, the southern main branch of the Rangitata, and in the valley of the River Tasman, forming Lake Pukaki, near Mount Cook, the latter being without doubt the continuation of the former. Without swelling this memoir with details, I may say that the Alps consist of a continuation of anticlinal arches and synclinal troughs, but instead of finding the mountains to be formed by the arches and the valleys by the troughs, my observations showed the exact reverse.

The enormous mass of Mount Cook occupies a synclinal trough, whilst the broad valley of the Godley River runs along an anticlinal arch.

The occurrence of such tremendous changes by which the arches or mountains have been converted into deep valleys, and the troughs into high serrated mountains, will give us some faint idea of the amount of time which has elapsed, and the enormous waste which has taken place before the Southern Alps assumed their present form. It may be very possible that the arches, having been shattered by the upheaval, gave way sooner to the united aqueous and atmospheric action than the troughs, which by their position were more sheltered.

It is certain, however, that at least the greater part of the original strata must have been removed, before our present Alps could have taken their present form.

In all these enormous chains, the absence of limestone is very striking, even rocks with a calcareous matrix are wanting; only small veins of calcareous spar occur in a few places, but when we take a nearer view of the nature of the sediments which form the Alps, this absence is explained.

It is evident that we see before us the deposits, in shallow water, of rivers resembling those which at present fall into the sea at the East Coast; that the sea bottom underwent alternate periods of elevation and depression, the periods of depression, however, preponderating in length.

We perceive, moreover, that according to the state of the rivers or the changes of the currents, the character of the deposits also changed, the pebble bed and conglomerates representing the immediate neighbourhood of the rivers on the littoral zone, whilst the claysones and finely grained sandstones represent those regions where only fine muddy particles were deposited far in the paleozoic sea.

The constituents of the pebble beds and conglomerates give us a clear insight into the structure of the mountains from which they were derived, and the fact that these constituents are of the same nature as the rocks which at present compose our Alps, show us what an almost incalculable lapse of time was necessary for the formation of the stratified rocks which here form the upper part of the earth's crust.

These pebbles are principally clay slates, gray wacke slates, flagstones, sandstones in the so called gray wacke form, but sometimes more crystalline, quartz, quartzites, hornstones, &c.

Only in a few places was I able to discover amongst these pebbles any traces of hypogene or metamorphic rocks whilst in the unconformably overlying zone of lower carboniferous or upper devonian rocks, where large conglomerate beds also occur, granites, syenites, gneiss, and porphyries are very abundant.

From this we may draw the inference that the paleozoic rocks were, before the deposition of the carboniferous beds, broken through by hypogene rocks, without being at present able to say where these hypogene rocks were situated. Some of the pebbles of porphyry are of great beauty, but the rocks from whence they are derived have never been observed by me in situ, anywhere in New Zealand.