Art. XLVIII.—The Artesian-water Basins of the Heretaunga Plain, Hawke's Bay.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 37, 1904, Page 431

Art. XLVIII.—The Artesian-water Basins of the Heretaunga Plain, Hawke's Bay. By H. Hill, B.A., F.G.S. [Read before the Hawke's Bay Philosophical Institute, 19th September, 1904] Plates XXXIV-XLI. The Town of Hastings is situated almost in the centre of what is locally known as the Heretaunga Plain. Napier is at the northern end of the plain, and Pakipaki, for our purpose, may be set down as situated at the south end. Few persons, had they known the plain as it was even forty years ago, would have thought so many thriving settlements would have sprung up in what was at that time an area just emerging from the condition of impassable swamp. At the time of the arrival of the first European settlers in Hawke's Bay the fertile area that is now the pride of the district was an untrodden swamp. Only sixty years have gone by since then, and it must be evident even to those not given to careful observation that the changes mark a period of progress that

points to great future possibilities. It would supply an interesting picture if one could show the condition of the country generally when civilising man first entered on the scene. The plain between Farndon and Pakipaki was covered with raupo, flax, tea-tree, scrub, and bush, and was so ramified by overflow and swamp channels as to make it impassable to man or beast. The lower country about Meeanee, and between it and Napier, was an area of fairly deep water, and long after Europeans had begun to settle in the district large 5-ton boats plied between Napier and Pakowhai by way of Awatoto. At that time Pako-whai was a peninsula surrounded by water on three sides. In those early days there were no roads, and the natives themselves dwelt along the sea-beach, some at the mouth of the Maraetotara Stream, near the Kidnappers, and others at Te Awapuni, the present site of the Washout, and others at Maraetaha, in the Inner Harbour, and others at the small island on the Tangoio Beach, about eight miles or so from Napier. The Ngaruroro River then ran along the plain from Roy's Hill, passing between Hastings and Pakipaki, thence by way of Havelock it swept round the low flats that skirt the shingle-deposits that form the Tukituki in the vicinity of Te Mata, the river eventually reaching Pakowhai. There it was joined by the Waitio and other creeks, forming a deltoid area that can even now be traced across the country in the direction of Meeanee and Te Awapuni, near the Washout. The Ngaruroro changed its course at the time of the great flood of 1867, a year before the establishment of Hastings as a town. The present bed of the river is along the bed of the old Waitio Stream. Since the alteration of its course, the river has on several occasions broken through the right bank in the vicinity of Roy's Hill, thereby threatening a return to its old course. The Tutaekuri River has also played an important part in recent times in modifying the surface features of the plain. Formerly the river, which now enters the plain at Redcliffe, entered at the Moteo, and so formed the fan-like area between Fernhill and Crissoge. The wearing-away of the limestones at Puketapu altered the course of the Tutaekuri, but even now in time of heavy flood the river overflows at the Moteo, and sends great quantities of water and débris into the plain by way of Omahu. In the great flood of 1897 the overflow waters from this river joined with the overflow from the Ngaruroro near Crissoge and the old flour-mill in the vicinity of Papakura, and, running along the low-lying area at the foot of the Papakura Hills, spread over the plain and formed one immense sea-like area in the direction of Meeanee, Pakowhai, Clive, and Te Awapuni, or what has since become known as the Washout.

The Tukituki River at first glance does not appear to have played such an important part in plain-building as the rivers already dealt with. The Tukituki did not always run through the gorge-like country at the place where the river enters the plain near Te Mata, on the south side of the plain. The limestones in the hills behind Havelock tell a story of past change. They are sadly broken and fractured along their highest parts, and, as seen from Hastings or Napier, appear to sink underneath the Heretaunga Plain in the direction of Roy's Hill. But towards the south-east they present a scarp of 200 ft. or more in vertical height that forms the left bank of the Tukituki River as it flows through a comparatively deep gorge before it enters the plain. The scarp appears as if the limestones here had been broken off from the limestones on the right bank of the river by some upward pressure, thus giving them a high tilt or dip under the plain in the direction of Fernhill and Omahu. The great fracture in the limestones provided a way for the Tukituki to flow from large lake-like areas that at one time existed over the whole country about Patangata, Waipawa, and Waipukurau, following the period when the great waterway through the Ruataniwha to the Wairarapa was closed, and when the Ruataniwha itself became a large lake of great depth. The overflow from these waters entered the bay through what is now known as the Middle Road, between Havelock and Patangata, but this line was changed when the limestones were fractured along the line extending from lower Patangata to Te Mata, on the south side of the Heretaunga Plain. Now, the changes that have taken place in connection with the three rivers named are of a comparatively recent date. By this is meant that in comparison with other changes of surface over the district the building-up of the Heretaunga Plain does not express a long period of time in comparison with other earth-changes. As viewed from our own immediate standpoint, the present plain presents certain characteristics, and we are aware of changes taking place in the surface-features of the country, as the direct result of material that the three rivers bring down on to the plain in times of flood, the Tukituki from the Ruahine Mountains, the Ngaruroro from the vicinity of Kuripapango, and the Tutaekuri from the Kaweka Mountains. At the present time a large portion of the Heretaunga Plain, as already pointed out, has been drained and made fit for the abode of man. There yet remains, however, a fairly large area of unmade plain, which is now in process of formation, the portion known as the Whare-o-Maraenui Swamp area being dealt with by mechanical means. This portion of the plain contains over 1,700 acres, and it is the property of the Napier

Harbour Board. This special swamp-area supplies an excellent example as to the amount of material that the rivers bring down in times of flood. It has been explained that formerly 5-ton boats plied between Napier and Pakowhai, and the whole of the swamp-area consisted of little else than fairly deep water. As floods took place, heavy deposits of silt, &c., were left in various places, and at times the land was raised many feet in height. Thus the area now under notice has been raised so rapidly that a syndicate a few years ago undertook the heavy responsibility of reclaiming the swamp and raising 300 acres of it a foot above the flood-level of 1897 within five years, whilst the remaining acres were to be improved and made capable of cultivation. In other words, the land was to be so improved under ordinary conditions as to be capable of occupation. The work that has been carried out since the arrangement was made supplies matter of much interest and of public value, and gives a clue as to the time that it would likely take to build up a plain such as the Heretaunga Plain presents to-day, assuming that the physical conditions in this Island have undergone no material modification. Even a cursory inspection of the Heretaunga Plain is sufficient to show an ordinary observer that the plain is bounded by hills which appear to be continuous with the sea-cliffs that bound the northern portion of Hawke's Bay in the direction of Petane and Wairoa, and that continue round the Inner Harbour to the Quarantine Island, the land just emerging above sea-level between the latter island and the Taradale Road, where a branch road running to Wharerangi has dammed back the sea in recent years; but the brackish creeks that reach the base of the hills towards Halliwell's and the vineyards at Taradale bear testimony to the fact of sea-action in times past, and that in the same way the sea-waters had swept the foot of the Taradale and Redcliffe Hills, and thence by way of Papakura had swept the whole of the area of what is at present known as the Heretaunga Plain, even running far into the channels to the westward of Pakipaki and the north-west of Maraekakaho. At the time small bays were formed, and there existed the islands of Fernhill and Roy's Hill, just as there exist Scinde Island, the Watchman, and others in the Inner Harbour. If we follow the line of hills that reach the plain between Maraekakaho and Pakipaki, and thence to Pukahu, Havelock, and the Kidnappers, and imagine for the moment that the plain has disappeared, it will at once become apparent that what are now low-lying hills on the north and west of the Heretaunga Plain were at one time cliffs presenting a face to the ocean as bold and as rugged as the Kidnappers do to-day. But the cliffs and the hills themselves will even now help us to determine the question that we have to decide, as to the geological,

history of the area known as Hawke's Bay and the Heretaunga Plain. The two have a similar history, and must be read together, although they are to-day so unlike. The present Heretaunga Plain was at one period a mere portion of Hawke's Bay. The whole of the area extending from Mahia Peninsula to Maraekakaho was once covered with land, and formed a portion of the East Coast district. Then came a period of subsidence along the east coast, and of elevation in the direction of the Ruahines and the Kawekas, and great changes took place in the surface-features of the country between the rising mountains in the west and the subsiding coast area. In order to make these statements clear we must see what the rocks themselves tell of the story of the past; for it is largely by means of what is left that we can tell something of what once was. A visit to an old castle-ruin does not show us the stately scenes that once took place in the banqueting-hall; but a study of the social life of the period when the castle was built will enable us to dovetail some of the doings of the people so as to form a complete whole of what is to-day a mere ruin and desolation, and our own imaginings will do the rest. Geology speaks in the same way. Every rock and every stone tells a history, just as the lower hills at Havelock, at Redcliffe, near Taradale, and the cliffs at the Kidnappers, tell a story that cannot be misread by those who are anxious to discover truth as supplied in nature's storehouse. All the lower hills near Havelock are made up of shingle-deposits so recent that Mr. Leipst, the noted well-sinker of Hastings, brought up with his machine a few days ago from a depth of 200 ft. a part of the bone of a bird (probably a kaka) in a well that he is sinking at Te Mata. Similar shingle and pumice deposits appear at Redcliffe, near Taradale; and if we go along the beach from Mr. F. Gordon's station in the direction of the Kidnappers we shall find scores and scores of feet of shinglebeds, pumice-beds, and other beds, deposited as regularly as if they had been arranged by human hands. In Napier the merest remnants of the shingle-beds remain, but when found they tell the same kind of story as do the shingle-deposits at Havelock and the Kidnappers. And so of the islands in the Inner Harbour, the cliffs bounding the harbour, as at Maraetaha, Petane, and along the shore hills in the direction of Tangoia: all present similar characteristics, all show deposits of shingle and pumice, and all present to the bay a vertical face, as if they had been cut away by means of a sharp knife. Try to imagine Hawke's Bay, or, rather, the Hawke's Bay extended district such as it was when the bay that is now covered with water was covered with land. The locality known as the Kidnappers continued north-north-east to Portland Island, and

the Mahia and the intervening area was covered with blue-clay sands and marls, or with limestones. It was at this period that great changes began towards the interior of the Island. The volcanic district was the centre of unusual disturbances, and the country between it and us was broken, and swept by floods of shingle and sand, alternating with showers of pumice, that spread over the country to the northward of parallel 39.40° S. At that time the watershed of the Taupo country was directed towards the north-east, and it was from the country in the vicinity of the present Mohaka River source that the heavy deposits of shingle and sand appear to have come. The shingle and pumice deposits extend from Pohui, at the base of Te Waka, on the Taupo Road, south-west along the Matapiro country into the Ruataniwha Plain, and thence generally southward, replacing the limestones that flanked and that also covered at one period what are now the Ruahine Mountains. Similar deposits fanned to the eastward, and spread as far as the Black Reef at the Kidnappers, the shingle and sand deposits between Pohui and Petane, along the present Napier-Taupo main road, being very largely developed. It was following the comparatively rapid deposition of shingle, sands, and pumice that the period of subsidence began which ended in the complete disappearance of the immense area extending from the Mahia Peninsula right away to the hills between the present Pakipaki and Maraekakaho, whilst the rifts or fractures that were made extended from Pakipaki to the Te Aute Lake, and from Maraekakaho on and on in an irregular line into the Ruataniwha district, where subsidence took place in a large measure corresponding and parallel with the line of elevation now known as the Ruahine and Kaweka Mountains. As remarked already, during the subsidence areas like Scinde Island, Fernhill, Roy's Hill, the Watchman, and a number of others of less importance became islands, separated from the mainland and washed by the incoming ocean. The subsidence of such an extent of land as covered Hawke's Bay and what is now the Heretaunga Plain, in combination with the volcanic disturbances that continued in the centre of the Island, brought changes in the surface-features of the country that have resulted in what is now recognised as the river system of Hawke's Bay. The Tukituki River, even after the disappearance of the river which I may call the Great Wairarapa, of which it formed a tributary, continued to flow southward, but the throwing-out of heavy fanlike deposits from the rising Ruahines, by means of the mountain-streams flowing eastward, eventually dammed back the main river at the south end beyond Takapau, and thus formed the Ruataniwha into a large lake. The filling of this lake, and its eventual overflow at what are now

the Waipukurau and Waipawa Gorges, led subsequently to the formation of large and important lake-areas—in fact, a chain of lakes—between Waipukurau and the gorge north of Patangata, and the surplus waters from these lakes reached the sea, some in the direction of Te Aute, some through what is known as the Middle Road leading from Havelock to Patangata, and some through the hills in the direction of the Kidnappers. But the fracturing of the Havelock limestones, and alterations in the level of the Te Aute Valley rift, caused the diversion of the waters into what is now the bed of the Tukituki, thus causing the disappearance of the chain of lakes that are easily traceable to-day. The Ngaruroro and the Tutaekuri formed a single tributary of the Great Wairarapa, but following the period of subsidence they became separate rivers and entered the then Heretaunga Bay, the Ngaruroro to the westward of Maraekakaho, and the Tutaekuri at the Moteo, where it eventually filled up the fanlike area between Fernhill and the mill near Crissoge. We have now to consider the growth of the plain that has been built up, not, it may be, phœnix-like on the remnants of a subsiding area, but yet at a rapid rate considering that only the rivers named have played any part in the work of rebuilding and reconstruction. To make the matter clearer, it should be stated here that what is ordinarily known as the Heretaunga Plain is, from a geological point of view, only a portion of it. The area of deposition, and not merely the area that we know has been raised above sea-level, is the subject of our inquiries. As one portion of an area is being raised above the level of the sea, another portion, and in fact other portions, are receiving deposits that are tending to raise them up to water-level, and it is necessary, therefore, in considering the growth of the Heretaunga Plain, to see how far that growth has affected the bay that at present extends beyond the limits of the Heretaunga Plain. In times of flood the waters that reach the plain not merely overflow and spread fanlike deposits made up of the materials brought down, but the waters passing slowly into the sea carry much of the fine sediment to be deposited at varying distances and depths from the mouth or mouths of a river. Those who have ever watched the formation-work as carried on by navvies when a railway is in course of construction must have noticed the carriage of material in trucks to be thrown down an embankment when being formed as a part of the permanent-way. Many loads of material are slowly thrown down before the horizontal movement takes place, but the filling-up is certain, and, as the necessary level is reached, the material continues to be thrown down to widen and form a base that

is much wider than the level way under formation. This process in a large measure illustrates the growth of the Heretaunga Plain. The material that the rivers brought down spread out fanlike in different directions, and, as the area of deposition filled up, the river was extended seaward, and it may be that the direction of deposition was altered or modified. This is plainly seen in the case of the Rivers Ngaruroro, Tutaekuri, and Tukituki, which have frequently altered their course, so that the fanlike deposits have spread themselves in large measure over the whole of what was a sunken area that extends from the fractured limestones at the back of Havelock to the limestones between Crissoge and Roy's Hill—that is, from north-west to south-east. It is the deposition of the material from the rivers that has produced the bedding from which the artesian-water supplies are now obtained, and the varying character of the material brought down will help to explain why the whole of the beds underneath the surface are made up of similar deposits. Recognising, then, that as the filling-up process went on the sea was thrown further back by the making of the land, there will be little difficulty in understanding how at the present time the plain of which the occupied part is known as the Heretaunga Plain is a good deal larger than that which is at present above the level of the sea. For purpose of reference, let the place locally known as the Washout, near Waitangi, be taken as the starting-point, and let us suppose that a place out in the bay is selected, fourteen miles away, and eight miles to the north-west of the Kidnappers. This area is almost a counterpart of the Heretaunga Plain. The depth of the sea fourteen miles from the Washout in the direction of Mahia Peninsula is 168 ft. At twelve miles the depth is 144 ft., at ten miles it is 108 ft., at eight miles it is 90 ft., at six miles 72 ft., at four miles 60 ft., at two miles 48 ft., and at one mile the depth is 24 ft. Suppose there was no water over this portion of the bay, the land would be as flat and the slope as gradual as the Heretaunga Plain itself between Roy's Hill and Waitangi. This plain was formed in its greater part under similar conditions to the Heretaunga Plain, and, geologically considered, is contemporaneous with it, and forms a portion of it. The shingle beach that is so characteristic of the coast between the Kidnappers and Petane forms no portion of the plain under notice. Its history is limited to the time when the Tukituki broke through the limestones at the gorge near Te Mata, and subsequent to the final separation of Scinde Island from the mainland in the direction of the Quarantine Station. The shingle along the beach is limited both in breadth and depth,

and began to be formed when the larger portion of the plain was above water, as the exposure of the beds at the Washout in the flood of 1897 clearly showed. If the shingle beach were taken away, just as we supposed the water for fourteen miles out in the bay to be taken away, there would be a valley-plain thirty miles in length and from eight to ten miles in breadth, so flat and sc gradual in the slope of the bedding that it would be impossible for the most perfect eye to distinguish the inclination of the beds. The character of the beds as they slope gradually into the bay will be better understood by pointing out a few facts as to the present height of the Heretaunga Plain. Roy's Hill is situated on the right bank of the Ngaruroro River, and is the last hill on the right when proceeding along the plain to Maraekakaho. Between it and the latter place the Ngaruroro River on several occasions has broken through the right bank in time of flood, and an embankment has been constructed for protective purposes. At this place the height of the plain is 166.4 ft., and it may be set down as the highest portion of the plain. The distance from the Washout at Waitangi is about fourteen miles in a straight line. From Roy's Hill to Pakipaki the distance is about eight miles, and from the latter place to the Washout is about twelve miles. From Roy's Hill to Havelock the distance is about eleven miles, and from Omahu Bridge to Havelock the distance is 7.75 miles. Now, Pakipaki is 32.39 ft. above sea-level; West Hastings is 44 ft.; East Hastings at the junction of the Havelock and Karamu Roads is 39.9 ft., and at the Havelock Bridge over the old bed of the Ngaruroro the height is 34 ft. above sea-level. Omahu at the bridge is 73 ft., at the Pa 63 ft., and at the old mill near Crissoge the height is 48.2 ft. Papakura is 36 ft., Redcliffe near the bridge is 25.25 ft., and Pakowhai is 18.5 ft. At the junction of the Hastings-Havelock roads, near the Mangateretere Public School, the height is 15.5 ft., and at the Clive Bridge Hotel the height is 11.5 ft., whilst at the Waitangi Bridge near the Washout the height is 7.25 ft. Taradale, at the junction of the Napier and Meeanee roads, is 16.75 ft.; at Meeanee, near the hotel, the height is 5.5 ft.; and at Awatoto it is 7 ft. These facts as to the height and general slope of the plain that is already above sea-level are supplied by Mr. J. Rochfort, C.E., and they will enable us to interpret something as to the quantity and character of the material that has filled up a whole arm of the original area of subsidence in a fairly regular sequence of beds that get deeper and deeper as they run seaward, and eventually die out in the bay at a distance that may be fairly set down at fourteen or fifteen miles from the beach that runs between the Washout and Awatoto. Underlying this immense accumulation of deposits is the old sea-bottom, made up of blue

clay and brecciated limestones that extend in all directions underneath the sea, the limestones, and the plain, and is really the basin in which all the artesian-bearing beds have been deposited. The most sudden slopes in the plain are between Roy's Hill and Pakipaki, where in a distance of eight miles there is a fall from 166.4 ft. to 32.39 ft., or nearly 17 ft. to the mile, and between Roy's Hill and Omahu Pa, where in a distance of six miles the slope is 103 ft., or 27.17 ft. to the mile. Between Roy's Hill and Hastings the slope averages about 16 ff. to the mile, so that the Hastings slope in reality represents the middle of an immense fanlike area with its pivot or centre at Roy's Hill and the fan spreading from Omahu Pa to Pakipaki with a gradual tilt towards the latter place. If we keep in view the general slope of the plain as shown here, it will be evident that the filling-in of the plain was rather by way of the old course of the Ngaruroro, and that the filling-in was greatly assisted by the Tutaekuri, which came down from the Moteo and joined the Ngaruroro in the vicinity of Omahu. The Tukituki rendered no help in the formation of the western part of the Heretaunga Plain, but its burden of shingle, deposited in a fan-formation from Te Mata, diverted the course of the Ngaruroro, turning it northward when in vicinity of the old mill at Havelock, and this was the general direction of the latter river until the year 1867, when it was diverted into its present bed. If we follow to their sources the three rivers that pass across portions of the Heretaunga Plain, it will be found that only the Tukituki had its origin of a chainlike lake formation from the time its waters reached the Ruataniwha. The Ngaruroro and the Tutaekuri rush from the mountains through a deep gut without the trace of a valley formation, and the high angle of slope will be seen by reference to a map showing the Ngaruroro from its rise at about 1,800 ft. above sea-level to the sea, a distance of sixty miles. The basinarea of each of the three rivers is as follows Tukituki, 937 square miles; Ngaruroro, 836 square miles; and the Tutaekuri, 326 square miles: or a total of 2,099 square miles. The latter rivers run mainly through a shingle and light sandy country, covered here and there with a yet lighter pumice sand. The deep gorge-like bed of each river shows how rapidly the rocks are wearing away, and this process is greatly assisted by the high angle of inclination of the upper part of each river, which enables even the heaviest timber to be carried in time of flood. Thus the Ngaruroro from its source at the back of the Kaweka Mountains as far as Omahu has a fall of 40 ft. per mile, but between Omahu and Pakowhai the fall is suddenly reduced to about 8 ft. per mile, and for the remainer of its course the

fall is less than 4 ft. to the mile. A similar remark applies in the case of the Tutaekuri River, but not in the case of the Tukituki. Now, the Ngaruroro and Tutaekuri Rivers bring down large quantities of fine material from the back country, where comparatively soft rocks abound, and we find that in times of heavy flood many hundreds of acres of temporarily submerged land are considerably raised, and therefore improved. But this improvement is at times a great loss to settlers who may be residing in the lower basin of these rivers. The slope or fall in the case of each river is much greater than it is with larger and more important rivers in Europe and America, for few of them have a fall of more than 24 in. to the mile, but the Ngaruroro and Tutaekuri, even when nearing their entrance to the sea, have a fall of nearly 4 ft., or 48 in., to the mile. How, then, comes the trouble from overflow in times of an excessive rainfall? The answer is to be found in the difference of slope or inclination between the upper and lower course of each river. In the upper course the water rushes down at a great speed, owing to its high inclination, and the carrying-capacity equally with the denuding-capacity is very considerably increased. Thus it comes to pass that what is easily carried by the River Ngaruroro in that part of it where the inclination amounts to 40 ft. to the mile cannot be carried where the inclination diminishes to 6 ft. to the mile, and finally to 4 ft. The rate of flow is stayed, and the carrying-capacity is diminished, so that flooding and the deposition of silt must immediately follow. It is for this reason that there has been so much spreading of material as soon as the flood-waters have reached the present plain-area, and the filling-in of one area has only opened a way for an adjoining area to be similarly dealt with; and this will explain in a large measure why there is so much general likeness in the beds that go to form what is known as the artesian basin. It would be impossible to suppose that the beds forming the Heretaunga Plain should be identical. The surface material of the plain to-day varies in quality and variety of material for the reason that deposition has taken place at different times. Speaking generally, there is comparatively little alteration in the character of the underlying water-bearing beds between Napier and Pakowhai, but they vary considerably in the direction of Redcliffe and West Clive. In other words, the beds in the general direction of the dip show more points of agreement than do the beds in the direction of their troughing. And just as the wells vary somewhat in their bedding, so also do they vary in depth. But the changes, whether in the depth of the waterbearing beds, or in the varying characters of the material passed through in the process of sinking, are only what might have been

expected under the conditions of deposition, but more particularly in the case of wells along the line extending from Clive to Taradale, as these places are towards the points of the troughing of the underlying beds, between which points the tides flowed when the Heretaunga area was an arm of the sea. Commencing, then, at Pakipaki, which is 32.39 ft. above sea-level, artesian water is found at depths varying from 65 ft. to 80 ft., or an average depth of 72 ft., according to the point selected. This depth gives 42 ft. below sea-level, or about 208 ft. below the highest point on the plain. The depth corresponds to a spot in the bay somewhat less than two miles from the beach at Te Awapuni. At the Pakipaki Pa, and near the railway - station, the water flows several feet above the surface, but this overflow disappears on approaching the entrance to the Te Aute Valley in the direction of what was once the Pakipaki Hotel. At Pukahu, and at the railway - crossing, Longlands Road, about midway between Pakipaki and Hastings, water is obtained at depths varying from 80 ft. to 110 ft., or from 55 ft. to 60 ft. below sealevel, with a flow rising from 4 ft. to 8 ft. above the surface. The depth in the wells in these places corresponds to a point in the ocean four miles from the beach at Te Awapuni. Hastings may be set down as being 40 ft. above sea-level, and artesian water is obtained at depths varying from 130 ft. to 160 ft., in what is known as the first water-bearing area. Other supplies have been struck in deeper sinkings at 280 ft., at 404 ft., and at 529 ft., but for the present the first water-bearing beds will suffice. The depth of the latter bed corresponds to the depth of the ocean nine miles from Te Awapuni Beach. Pakowhai is 18.47 ft. above the sea, and artesian water is reached at depths varying from 140 ft. to 170 ft., or, say, 137 ft. below sea-level, and 303 ft. below the highest point on the plain. This depth corresponds to the depth of the ocean between eleven and twelve miles out in the bay. Te Awapuni is 7 ft. above sea-level, and water is reached at depths varying from 170 ft. to 200 ft. between this place and Awatoto. This depth corresponds to the depth in the ocean about fifteen miles out in the bay. The Napier artesian water is found at depths varying from 156 ft. to 240 ft., according to the proximity of the wells to the hills. There are water-bearing beds at a greater depth than this, but the upper bed corresponds with the line of water-bed that is first reached at Pakipaki. The height of flow at Napier in the best wells reaches 30 ft. or more. As we proceed from Napier or from Te Awapuni in the direction of Taradale, from Pakowhai in the direction of Redcliffe, from West Clive in the direction of the Grange and the Big Bush, and from Hastings in

the direction of Omahu, the depth of the wells diminishes with great regularity. Thus, at Meeanee the wells are 160 ft. deep, at Roseneath (midway between Meeanee and Taradale) they are 100 ft., whilst they vary from 60 ft. to 90 ft. at the latter place. At the site of the old Farndon Hotel the artesian well is 135 ft. in depth, at West Clive water is reached at 130 ft., at East Clive 90 ft., and at the Grange and in the vicinity of the Big Bush at depths varying from 60 ft. to 85 ft. The variation in depth at the places named corresponds to what might have been expected from the troughing of the beds in the directions indicated already. It will be noticed that the increase in the depth of the first water-bearing bed from Pakipaki to the sea corresponds in a striking manner to the slope of the plain between Roy's Hill and Te Awapuni, as also to the increase in the depth of the sea along the area of depression. But we are led to assume that the same saturated bed supplies the whole of the wells of the first series by reason of the fact that they all have the same height of flow above sea-level, if allowance is made for friction in the different wells, as they deepen between Pakipaki and the sea. Perhaps the best illustration of troughing and of the same source of supply is to be found in Napier itself. It is not necessary to refer in any detail to the number of wells within the Borough of Napier, but so long ago as 1888 several 6 in. wells were put down in Monroe Street. At the first well in the street towards Clive Square, and 24 chains from the hills, a 6 in. well was put down, and water was struck at 156 ft. A second well was put down 14 chains further along the street in a south-east direction, and water was struck at 196 ft. The value of these wells from a scientific standpoint was enhanced by the fact that three years earlier a well had been put down at the junction of Hastings and Munroe Streets, which is just 19 chains further to the south-east, so that three wells in the same straight line gave the following depths: First well, 156 ft.; second well, 196 ft; third well, 240 ft.; whilst 33 chains separated the first and third wells. The same water-bearing beds clearly supplied the three wells, as the height of flow was similar, and the striking of water in the second well perceptibly influenced the flow in the first well, as it did also the flow of other wells in the immediate vicinity. It seems to me that the upper water-bearing area over the district is connected, but it is certain that there are also areas where water is available which appear to be isolated and very limited in extent. Thus, in the case of Havelock, the wells between Hastings and the bridge that crosses the old bed of the Ngaruroro in the direction of Havelock are clearly connected, but the wells that have been sunk in Havelock itself are of varying depths, and must either belong to a second water-bearing

area or to a separate supply-basin. Thus, a well put down for Mr. McHardy reached 403 ft., and the water rises more than 30 ft. above the surface. Canon St. Hill's well is 400 ft., and the rise above the surface is 35 ft.; and yet near by another well was tried to the depth of 482 ft. without finding water. The well near the Havelock Hotel is 325 ft. deep, whilst one put down in Cemetery Road for Mr. Beecroft is only 177 ft. These varying depths show how necessary it is to keep records of all facts connected with the sinking for artesian water, as they not only supply important data that is of value to the geologist, but they eventually lead to generalisations of the utmost moment to settlement. In other papers dealing with the subject of artesian wells I have dealt in detail as to the probable source of supply of the waters, and of the effect of high tide and of rainfall on the increase and the height of flow, and it is not necessary to deal further here with these aspects of inquiry. My purpose has been mainly to show how the surface features of a country are ever undergoing change, and how these changes in a large measure are modified and even brought about by movements and changes that may be hundreds of miles away. It has been a long time since the Kidnappers, Portland Island, the Mahia Peninsula, and the north-western portion of the present bay were united, and formed, with the present Heretaunga Plain, an area covered with limestones and other rocks. The subsidence that took place at that time was balanced by great changes to the westward and towards the centre of the Island, and since then the altering of the watersheds has brought about the partial refilling of the subsided area, and has given this district the magnificent Heretaunga Plain, with an equally magnificent artesian-water supply, the value of which it would be difficult to estimate. Nature's work is by no means completed. The filling-up of the Whare-o-maraenui Swamp will be a great work, and those who have undertaken it deserve success, for they have already earned it. But when the Whare-o-maraenui Block has become the abode of industrious settlers, the rivers will continue to carry down their burdens of fertility in times of flood, and deposition must and will take place within areas that will vary just as the areas have varied ever since the filling-in began. Observations, the recording of facts, the recognition of common interests and common benefits, will bring into play that foresight which will tend to minimise the destructive effects of heavy floods, whilst the plain will continue to extend by the filling-up of the Inner Harbour, for this is the next great work that the rivers Ngaruroro and Tutaekuri will accomplish. I purposely leave the interesting work in connection with the filling-in of the Whare-o-maraenui for another occasion.