Geological and other Reports
I. — Report on the Wairarapa and East Coast
Report on the Wairarapa and East Coast.
After returning from the exploration of the Valleys of the Akatarewa and the Waikanae rivers, I started from Wellington on the 15th of January, with the view of gaining an insight into the geology of the N.E. part of the Province, more particularly in the direction of the Puketoe range, and the country generally, lying between the Tararua range and the East Coast.
Leaving the drift gravel of the Wairarapa behind me at Masterton, I found on rising the bills towards the Taueru station, that I had entered upon the upper tertiary sandstone. This rock I found extending over the whole of the interior of the North-Eastern district, resting upon the blue clay except where some drift gravel intervened between the two, but the gravel is by no means largely developed in this district. Towards the East Coast I found a change of rock, but of this more hereafter.
This upper sandstone consists of a series of soft fine grained sandstones, fossiliferous and alternated with fossil beds almost approaching limestone, and is sometimes of great thickness in this district, seldom less than 500 feet, and in some places I think it must measure 1000 feet.page 48
Some of its fossils are turritella, venus, dentalium, pecten, struthiolaria, I have no doubt that it is of the same age and character as the upper sandstone of the Whanganui river.
This formation, where found undisturbed, seems to lie very horizontal; but numerous hill sides have slipped into the valleys, there giving the strata the appearance, to the casual observer, of dipping in various directions and at high angles.
From the vertical nature of the section in which this series is found exposed, it has been impossible for me to make any but a partial investigation of its different beds, and the same difficulty, you may have perceived in the cliffs of the Whanganui and other Western rivers.
The blue clay throughout this district does not show much of its thickness above the river levels.
Crossing the Manuka range, 906 feet above the sea level, the road drops down to the Valley of the Taueru, and thence on to the Taueru station.
Here I visited a very beautiful waterfall, formed by the waters of the Mangarei, a tributary of the Taueru. The stream falls over a ledge of the upper sandstone to a depth of about fifty feet, into a large circular pool. Hard fossiliferous beds of the upper sandstone form the rocks at the fall, the softer overlying beds, which are found in an adjacent cliff, having been denuded.
I may here state that there is a remarkable parallelism between the effects produced in this district and in that of the country inland on the Whanganui and Rangitikei rivers, inclusive. In both districts are the upper sandstones largely developed, and in both have these nearly horizontal strata been broken up by denudation, into very rugged surfaces.
Many of the beds of the upper sandstone are extremely soft, and therefore liable to be rapidly worn away; some of them, indeed, on being struck by a hammer, instead of breaking into fragments, crumble and run down into pure sand; and water poured upon them passes through as in a sieve.
At the Taueru pieces of marine fossils were shewn to me as quartz; and I found that generally throughout the district calo spar, white limestone, or, as I have said, even fragments of fossil shells, were supposed to be quartz.
Some very perfect “pecten,” from the top of the Maunga Pakeha range, were presented to me by Mr. Varnham, for the museum in Wellington.
On the 19th January, I left the Taueru station and proceeded up the valley of that river, the Forty Mile Bush lying about three or four miles on my left and here covering a very broken country.
The road leads past Mr. Nicholl's, crosses the Taueru, and ascends the ridge on the Eastern side of that river. My estimate of the height of the Taueru station above the sea is 427 feet. The ridge just mentioned rises to 1100 feet, and the Manawa hill next to it, above a run which rejoices in the euphonious name of Boggley Wallah, to 1179 feet. Here one looks down upon Messrs. Jeffs and Riach's head station, and on the valley of the Whareama, with its level flats and swamps, while to the Northward may be seen the country drained by the Matai kuna, the Oahanga, perhaps also the Akiteo and here I could see plainly enough that all within view was of tertiary age, except the blue ridges of Tararoa in the far distance.
At the Manawa hill, I was lucky in meeting Messrs. Spinks and Langdon, proceeding in the direction in which I wanted to go, viz, to Mr. Spinks' out station, Mount Pleasant, or Waitawiti. Our road passed over the highest ridge which I traversed in the district, viz Ngatakitura, which, by a mean of two observations, I make 1210 feet above the sea. From this ridge we descended to Mount Pleasant which is probably the highest inhabited European house in this island, being also by a mean of two observations, 985 feet above the sea level. Notwithstanding the height, it is a very cheerful looking place and it commands an extensive view.
Leaving Mount Pleasant on the 20th January in the direction of Knight's station, we soon crossed the sources of the Taueru, passing therefore again to the Westward of that river, crossed a ridge and came upon the flats of the Waitawiti a tributary of the Tiraumea. As the latter river is a large branch of the Manawatu, we were now therefore, on Western waters.
We crossed another ridge and descended to the Tiraumea, at Knight's station, where the Waitawiti joins that stream. Our descent had been considerable, and Knight's house, by a mean of two observations, is only 414 feet above the level of the sea. Thus it appears that the gorge of the Manawatu must be considerably lower than that height.
The country here is better and less abrupt than that lying further to the Eastward, but it is close to the forest of the forty mile bush.page 49
When the forty mile bush road is made I should suppose it would be easy to open a branch line, by or near the Tiraumea to Knight's station, which would then form the easiest line to the Wairarapa for a good deal of the open country.
An open track of a few thousand acres, called Moroa, lies surrounded by forest, between the Tiraumea and the Taueru, about six miles below this.
The Tiraumea has at present very little water in it, but I am informed that in a fresh, canoes can ascend about three miles beyond Knight's.
In its bed I found a boulder with plant impressions.
I would now call your attention to the Puketoe range, which has been in sight for the last two days, and where we may be said to have arrived, for Knight's station is on its lower spurs. I believe a great deal has been expected from this range in a mineral point of view, perhaps because it is remote, and difficult of approach. My first view of its outline settled its character in my mind and a close approach confirms the first view.
It is clearly tertiary, of the same age and character as the country I had traversed, but attaining a somewhat greater elevation. The additional height and its scarped cliffs, lead me to suppose that it marks a line of fault, or slip. I need hardly add that metals cannot here be expected.
The ascent of the Puketoe from Knight's would be troublesome, although the distance is short. A succession of sharp wooded ridges intervene. It looks to be easier of access from the North East.
I do not suppose the height of this range to reach 2000 feet. Supposing it to be 500 feet higher than Ngatakitura, this would give an elevation of 1770 feet above the sea. There may be some open land on the top of the range, but the greater part is covered with bush.
At Knight's I found the blue clay, and on the ridges above, upper sandstone beds, with turritella, venus, struthiolaria &c., From Knight's it is impossible, at present, to get a horse through the bush to the gorge of the Manawatu, which, as the distance is short, might be easily rectified. The view this day extended over the sources of a number of rivers, the Tiraumea, the Taueru, the Whareama the Mataikuna, the Oahanga, and perhaps the Akitio: open country to the Northward and Eastward, bush to the West, beyond which the Tararua is seen in the distance. On the Tiraumea there appears to be a good deal of totars.
From Knight's I returned to Mount Pleasant.
It had often puzzled me why the alluvium of the Wairarapa should be of such a different character to that of the Hutt, but I think I have now solved that problem. The Taueru from its source to its exit in the Ruamahunga, passes entirely through soft tertiary rocks, and I believe it to be from their degradation, that the peculiar character of the alluvium of the lower Rumahunga is derived.
On January 21st I left Mr. Spinks' hospitable mansion, and proceeded to the Eastward, again crossing Ngatakitura and Manawa ranges. From the latter the road drops down to the valley of the Whareama, near the junction of the Makirikiri with that stream.
Here I again found the usual upper sandstone fossils. About two miles further down I reached Ngapapatu, Messrs. Spinks and Langdon's head station, which I make only 143 feet above the sea level. I now began to perceive signs of a geological change. Still proceeding downwards I crossed the Whareama, passed over a hill and descended upon the Tinui station, situated upon the flats of that stream, a tributary of the Whareama.
Immediately above the station is one of those remarkable hills called Taipos, which I accordingly proceeded to examine. These hills have an extremely fantastic, picturesque and rugged outline, and at first give the impression of volcanic peaks, but on examination prove to be our old friend the upper tertiary sandstone, tilted at an angle of about 70°, and dipping to the Westward; the harder parts of the strata sticking out in peaks, while the softer parts have been worn away.
On the top of the Tinui taipo I obtained turritella, venus, dentalium &c., Its height is 975 feet: Here also I found the Matai kuna taipo bore N 50° E, Buxtons taipos S. 20° to 30° W, and what I supposed to be Moore's taipos S. 15° W. W. It will thus be seen that the several peaks are nearly, but not quite, in a straight line.
Proceeding on the 22nd towards the coast, the road passes for a short distance up the valley of the Tinui, where I think I found the blue clay. Crossing that stream I ascended a ridge 828 feet high, where a fresh geological series is found, consisting of white limestone and calcareous grits, and in their midst, a fine grained greenstone, looking like a Syenite, which is doubtless the intrusive rock that has tilted the strata. It appears to have brought up the calcareous rocks, dislocating and tilting the upper sandstone at the same time.page 50
If you refer to my report of October 24th, 1861, you will perceive that I describe calcareous rocks, highly inclined on Messrs. Barton's and Riddiford's stations. White Rock and Teawaite. I had now clearly found the continuation of the same series, and more than that I had found “in situ,” the dislocating and upheaving rock. The Hornblendie pebbles found in the bed of the Upoko Ngaruru must also have been derived from another variety of the intrusive rock of the same age, and from my previous traverse in that direction, to Messrs. Beetham's station, I have quite sufficient evidence to establish a line of dislocation and upheaval, extending about N.N.E. from the White Rock and Teawaite stations, the action along which line has exposed a series of calcareous rocks, thrown up the strata of the upper sandstone at an angle of 70°, and probably bent and folded a series of tertiary rocks which I was now approaching on the East Coast.
Descending from the calcareous ridge to the valley of the Whakatake the road follows that stream to the sea, and thence South to Castle Point. We now find a series of thin and soft beds of sandstones and mudstones, cropping out on the beach and in the vallies, sometimes nearly horizontal, and sometimes inclined at high angles. What relation these rocks have to the limestones and calcareous grits, I am at a loss to determine, for I could not here find a section which would throw light upon the subject. My impression is that they overlie the calcareous rocks and at the period of dislocation were rucked up on the back of the latter by the force of the upheaving power.
In these sandstones and mudstones I found small seams of coal and numerous impressions of vegetation, but none clear enough to be enabled to judge of their age, but as the coal-seams appear to be lignite, or brown coal, I have little doubt that we may put them down as of tertiary age. In fact I believe them to be of the same age and character, as the coal shales of the Whanganui River, mentioned in my letter of February 17th, 1862.
The history and age of the calcareous rocks will I believe be best obtained on the Teawaite station, where they approach the sea. They must not be confounded with the upper tertiary fossiliferous limestone of Tepurapura and elsewhere, which seems to be found in patches only.
On January 23rd I examined the reef at Castle Point. This reef is a peninsula forming the shelter to the anchorage. Both it and the rock called the Castle are composed of calcareous sandstone, resting unconformably on the sandstones and mudstones just mentioned. In it I found venus, pecten, terebratula, ostrea, turritella, struthiolaria, &c. The reef, which is a ridge perhaps fifty feet high, is penetrated by a cave, through which the tide passes and in which the roar of the wind and waves is very striking. Between the reef and the Castle Rock, the sea has another passage through the rocks into a basin. The Castle Rock is of similar formation to the reef.
In the mudstones and sandstones on the shore I found plant impressions, and in consequence proceeded in the afternoon up the bed of the stream behind Castle Point in the hopes of falling in with some seams of coal. I went on as far as I could penetrate, perhaps three miles, finding plenty of plant impressions, but no actual coal seams.
Mr. Guthrie informs me that some years ago, one of his shepherds, who has since returned to Australia, brought in a handkerchief full of coal, (stating that there was plenty more where he found it) which burnt well and seemed of good quality, and which must have been found within three miles of the Castle; but unfortunately he had neglected to ask him where he got it.
The coal question in the East Coast District may be put as follows.
My impression is that the mudstones and sandstones of the coast are of tertiary age and therefore if any workable coal seams are found in them, that the mineral will be of inferior quality, but there are the little known calcareous rocks to be considered.
Now, at the Kowhai coal fields in Canterbury, there are calcareous rocks in the vicinity similar to the white limestone of our East Coast, and although Mr. Haast, at the time of my visit to that coal mine, had been unable to determine any connection between these rocks and the coal, yet he had a strong suspicion that they formed part of the series. Consequently, although I have seen no indication of coal among the calcareous rocks of the East Coast, except perhaps at Teawaite, I think we have at all events some reason to expect the possibility of its being found; and as from the broken nature of the country it might take years for one individual to explore it thoroughly, I would suggest that a reward for the discovery of the outcrop of workable seams of coal, might stimulate the perceptive faculties of shepherds and others, whose daily avocations lead them through the defiles of these regions.page 51
On the beach here is some iron sand, whence derived it is difficult to say, unless it comes from the intrusive greenstone.
On the 24th January, Mr. Thomas Guthrie kindly accompanied me to point out some coal seams on the shore. Near the Nakaua river we found soft sandstones containing plant impressions and some coal seams about two inches thick. They were not continuous, but thinned out in a yard or two. The rocks are the same as those at Castle Point and dip slightly to the Westward.
Ascending from the beach in about a mile, I again came upon the calcareous grits and the intrusive greenstone, both of which prevail in crossing the Trooper, the ridge separating the Whareama from the sea. 896 feet I make the height of this ridge.
From this range the Puketoe is visible, its tertiary character evident from this distance.
Descending from the Trooper, I crossed the alluvium of the Wharehama Valley, and ascended the hill next to Buxton's Taipo, composed of calcareous grit. The Taipo has a singular family resemblance to that at Tinui and also dips to the Westward. I thence descended to Telford's station, Awa toe toe, 136 feet above the sea.
Leaving Mr. Telford's on January 25th, I continued on the calcareous grits for about a mile, when the upper tertiary sandstone rocks again appeared. and I found turritella, venus, &c. The upper sandstone now continues all the way to Collins bush, resting on the blue clay, or possibly in places on gravel.
The road crosses a ridge and descends upon Biscuit Creek, crosses another ridge and descends upon the Kaumengi, crosses a third ridge and descends upon the Taueru, crosses a fourth ridge and descends upon Te Ore Ore: the average height of the river flats being about 400 feet and of the ridges, where the road crosses, about 900 feet above the sea.
Reaching the Ruamahunga the upper sandstone has been left behind, and the drift gravel appears.
Stopping at Masterton for the night, I was informed that the plant beds of the East coast extends for a considerable distance up the Oahanga river.
In this journey I have settled the character of a large block of country, viz.,—the whole of the island within this Province lying to the N. E. of the Wairarapa, and between the Tararua and the East coast. It will of course be desirable to complete a traverse which I propose to make with you, from the gorge of the Manawatu to the Akitio river and the East coast, but as I have been through the gorge of the Manawatu, and as I have also been on the Rua Taniwha plains and at Porongahau, I may very safely venture to predict that in the above named traverse, we shall find nothing but the above described tertiary and other rocks.
In none of these tertiary rocks can metallic ores be expected, (although the intrusive igneous rock may contain a little gold), nor do I expect any in the limestones and calcareous grits, for the following reasons.
1st. Because I see no indications of mineral lodes among them.
2nd. Because, although I have been unable to detect fossils among them and therefore cannot as yet assign to them their geological age; if not older tertia ries, from their lithological character they can hardly be older than of Mezozoioc age, and therefore, supposing them to be of that age, although coal may be looked for, one cannot expect to find any of the metallic ores among them, save possibly ores of iron, of which however there is no appearance.
The date of dislocation and upheaval of these rocks would also, I imagine, militate against the argument of their containing metalic ores (there being no appearance of any previous disruption of these rocks which might have charged them with minerals). The intrusive plutonic rock must have penetrated them after the deposition of the upper sandstone, therefore probably in the Pliocene. or Post Pliocene era.
You will perceive that we have now established three nearly parallel lines of plutonic or volcanic action in this Province.
In the centre, the ancient rocks of the Rimutaka, Tararua, and Ruahine, with their spurs, folded and pressed together, and having a general direction of about N.N.E. true.
In the East, the calcareous and tertiary rocks, tilted on a line of about N.N.E. (magnetic) from the ancient rocks of Cape Palliser towards the Province of Hawke's Bay. In the West we have part of the volcanic chain of Ruapehu and Tongariro, ending abruptly, however, at the southern slope of Ruapehu, and perhaps I might include a fourth line in that neighbourhood, in the Kaimanawa range, but it is hardly in the Province.
From the central chain on both sides tertiary rocks extend East and West. I have therefore narrowed the area in whcih page 52 metallic ores may be sought to the main central range above described, the Kaimanawa range in the Taupo country and the Aorangi range at Cape Palliser, save and except the chances of finding gold below, or in, the drift of the Wairarapa and the West Coast.
On the 26th of January, I returned to Wellington, with the expectation of finding a report from Melbourne, upon specimens of rocks which I had sent there for examination; in this I was disappointed, and as I had a little time to spare before the arrival of another mail, and found that some curiosity existed as to the results of a recent journey to the top of Tararua, by the valley of Wai Ngawa, I proceeded to Greytown on February 3rd, with the intention of making the ascent of that mountain.
However, after several days attempt to get hands to accompany me, I found that owing to the harvest and the bush fires I could neither get white men nor maories to undertake the journey at this time.
Mr. Thos. Kempton, who offered to go as guide, gave me however a very clear andintelligent account of his late journey. He appears to have travelled up the bed of the Wai Ngawa for three days, before emerging from the bush, and at a great incline, he thinks often three feet rise for four in advance. He then came out upon a grass country, extending to the top of the mountain, the vegetation consisting of a new sort of tussae, the common spear grass and the broad leaved spear grass (no doubt the “Spaniard” of the Middle Island) and wild parsley, which I suppose to be anise. To any one who knows the Middle Island the vegetation speaks for itself. He had reached the zone of glass, above the usual forest zone.
Arrived at the top he saw range after range to the Westward, of the same character, with bald grassy tops above the forest zone, and apparently nearly, if not quite, of the same height as the range on which he stood which shut out the view of the West Coast.
It is evident enough that the grass country must be covered with snow all winter. If it can be made of use, Mr. Kempton recommends a line to be cut into it by a leading spur opposite Ray's. On the descent he found out a better line ef road which would shorten the ascent by a day. He describes the rocks as similar to those of the Rimutaka hill.
As all the rivers on that side of the Rimutaka and Tararua bring down similar gravel, this was to be expecied, as the parallelism of the formations is obvious.
I have honor to be
Your most obedient servant,
James C. Crawford