CHAPTER III

THE HOT SPRINGS OF VANUA LEVU

THE abundance of hot springs in Vanua Levu, and in fact in the group generally, is not commonly known. In the earlier accounts of these islands those of Savu-savu are often alone referred to, not only for this island but for the whole archipelago. The United States Exploring Expedition under Wilkes spent six months in 1840 in making a survey of the whole group. Yet Dana, who was attached to the expedition, remarks that “the only trace of actual volcanic heat which the islands appear to contain is found at Savu-savu Bay.”[14] Horne in his excellent account of the group, which he visited in 1878, was among the first to direct attention to the abundance of hot springs there; but he does not enumerate many. Although he travelled extensively over Vanua Levu, he refers to only three in that island, namely, at Savu-savu, Wainunu, and Vunisawana.[15] It will be shown below that most of the thermal springs discovered by me might easily have been overlooked.

Before dealing with those of Vanua Levu I will mention the other localities in the group in which thermal springs are from various sources known to me. They probably form but a small proportion of those that actually exist; but the list can be readily extended by those acquainted with special parts of the archipelago. In Viti Levu they occur amongst other places at Wai Mbasanga, on the Singatoka river (Horne) and at Na Seivau on the Wai Ndina, where Macdonald in 1856 found temperatures of 106° and 140° Fahr. in two different springs.[16] Mr. Thiele in more recent years referred by hearsay to some hot springs on the Wai Ndina.[17] Kleinschmidt in 1876 visited a hot spring near the village of Nambualu in the island of Ono which rose up in the midst of a brook and had a temperature of about 100° Fahr.[18] The same naturalist in July of that year, when accompanied by Dr. Max Büchner, came upon a hot spring issuing among the mangroves at the coast about a mile from the village of Ndavingele in Kandavu. He did not take the temperature; but he says that Colonel Smythe (about 1860) observed the temperature to be 144° Fahr.[19] Different writers refer to extensive hot springs on the island of Ngau. They are placed near the beach, and close to an ordinary cool spring. Miss Gordon Cumming in _At Home in Fiji_ gives an illustration of them. Horne mentions a hot spring on the island of Rambi. Andrews describes two others that bubble up through the limestone near the tidal zone in the southern part of Vanua Mbalavu. Both these springs are in close proximity to the junction line between the intruded andesite and the old reef rock. One of them, though not boiling, was hot enough to scald the skin.[20] This list is no doubt capable of being much extended, especially for Viti Levu and the Lau Group.

A description of the several systems of thermal springs of Vanua Levu will now be given.

1. THE HOT SPRINGS OF THE LOWER VALLEY OF THE WAINUNU RIVER.—This is one of the most extensive systems of the kind in the island. The temperature of the various springs during my sojourn in this district in 1898 ranged from 100° to 130° Fahr. Those known to me are mostly situated in the lower part and at the mouth of the Ndavutu Creek, one of the tributaries of the Wainunu. They open usually on the river-bank, either close to the water or a few feet above it, but some of them find an exit under water at the bottom of the river. Natives allege that hot springs occur at intervals on the left bank and at the river-bottom along the whole length of the river below Ndavutu Creek. There is certainly a hot spring on the right side of the river’s mouth near Mr. Dyer’s house. It issues from the reef-flat and can only be observed at exceptionally low tides. There is also a hot spring which rises up at the edge of the stream at Thongea (Cogea) nearly a mile above Ndavutu. If the above statement of the natives is correct, as I believe it is, then these thermal springs issue along a line quite four geographical miles in length extending inland from the mouth of the Wainunu.

All the springs are situated in the tidal part of the river-valley, with the exception of that of Thongea, which is just above this limit. They are but little elevated above the sea-level, those exposed being usually not more than ten feet above the river and often much less. This is a region of basalt, the valley of the Wainunu lying, as described on page 82, in the fold between two great basaltic flows, and probably representing a line of weakness, along which the hot springs issue either from among loose blocks, or from the soil, or from a tufaceous sandstone. They deposit little if any of the siliceous sinter which is often found in the thermal waters of this island. This is due probably to their scanty exposure and to their low temperature. The density of the water is near that of fresh water, being not over 1001. The following temperatures may be useful for comparison with future observations:

Thongea, when not covered by the stream July, 1898, 127° F. Ndavutu, bath-spring at Mr. Barratt’s house Usually 100° " " on left bank of the creek near the landing place June, 1898, 126° " " on left bank of creek near mouth Dec. " 127° " " pool in foot-path on left bank { June 2, " 112° " { July 27, " 111° " " at bottom of main river in depth of 3 feet, } close to the left bank and just above the } July " 122° " mouthof the Ndavutu creek, self-registering } Six thermometer used }

2. The Hot Springs of Natoarau and its Vicinity.—This thermal system lies in the lower valley of the Mbale-mbale branch of the river Ndreke-ni-wai. The principal springs are situated at Natoarau, a village about half a mile in a direct line from Mbale-mbale, about three miles from the coast, and only about fifty feet above the sea. They bubble up in pools near brooks, and extend at intervals over an area probably several hundred yards across. Five springs came under my notice; but there are doubtless several others in the low-lying and often swampy land of this district. No deposits were noticed, but the mode of occurrence and low temperature of the springs serve to explain this fact. The following temperature observations were made by me in March, 1899:—

A. Pool 4 feet across, with sides of stone, close to village 126° F. B. Pool 10 feet wide, a few paces from pool A 114° " C. Pool 12 feet wide, 100 yards from village, near the river 103° " D. Pool on the road to Mbale-mbale, mixed with surface water 100° "

The natives and others often state that the thermal springs here and in other localities are much hotter in dry than in rainy weather. This is correct in a sense, because in wet weather the surface water would usually find access to the pools; but there is no reason to believe that the temperature of the water at the hole of exit varies at all from this cause. The temperature of pool A was taken at the bottom where the water bubbled up; and probably it represents the true degree of heat of these springs, since in the other cases observation of this point was not so easy. The weather was dry during this visit; but, three months before, I tested the temperature of this pool after heavy rain, when the district was flooded, and then I got a reading of 127° at the exit-hole of the spring.

Another thermal spring, which is distant about a mile from Natoarau, is known as Waitunutunu, that is, Warm Water. It lies about a third of a mile from the village of Nambuniseseri, between Mbale-mbale and Waisali, and is quite four miles inland and about 100 feet above the sea. The springs bubble up into a pool, about 12 feet across, which is close to a brook and had a temperature in March, 1899, of 109-112° F.

3. THE HOT SPRINGS OF NUKUMBOLO.—The village of Nukumbolo, where the springs are situated, lies on the banks of a tributary of the Vatu-kawa branch of the river Ndreke-ni-wai, and is distant as the crow flies about six miles inland from the river’s mouth. The springs issue on a hill-slope from several places a few steps apart, and are removed about a hundred yards from the river, and from 20 to 30 feet above it. Their elevation above the sea would be about 130 feet. The temperature taken in the two hottest places was 157° F, in November 1898, and 158° in the following February. As in the case of the springs of Savu-savu and a few other localities, the rocks are coated with siliceous sinter mixed with carbonate of lime, and a gelatinous incrusting alga grows on the borders of tiny hollows bathed often in water of a temperature 137-140°, but thriving most where the temperature is 115-120°. The water runs down the slope into a series of pools made by the natives for bathing, the temperature of the lowest pool being 103-105° and of the highest 120°. This is one of the best localities I have seen in the island for the erection of thermal baths. The rock pierced by the springs is apparently a basic agglomerate-tuff. Large blocks of a hard and somewhat altered palagonitic tuff lie around the bathing pools.

4. THE BOILING SPRINGS OF SAVU-SAVU.—These springs figure in all the descriptions of the group, and they are also famous amongst the natives. Since they were described by Wilkes, who visited them in 1840, in his narrative of the United States Exploring Expedition, many accounts of them have been written by subsequent visitors; not infrequently they have been sketched as well as described; and several analyses of their waters have been made.[21] The accounts of these springs that lie before me extend at intervals over a period of nearly sixty years; but I shall allude to them only so far as they throw light on the history of the springs during this period.

The principal springs are situated in a slight hollow in a more or less level tract extending in from the beach, and are distant about 150 yards from the shore and about ten feet above the sea-level. They are five or six in number, and at the time of my visits in July and November, 1898, they were boiling briskly, the thermometer readings being 208-210° F., but the mercury probably fell two or three degrees in withdrawing the thermometer. When, as was the case when Wilkes visited this locality in 1840, there is but a slight appearance of boiling, brisk ebullition is produced by covering them over with leaves. The natives call this locality Na Kama, which signifies “the burning place,” and employed the springs extensively for cooking their food. Just as Wilkes describes, a freshwater brook runs past the springs and receives their outflow. The temperature of the brook immediately above the springs is that of an ordinary freshwater stream 75-76° F.; but below it is scalding. The account given by Wilkes of the spring and of the brook in 1840 applies to them in our own time. The small stones lying in the effluent channels of the springs are incrusted with siliceous sinter, and a green alga lines the sides, bathed generally in the steam but sometimes partially immersed in water only a few degrees below the boiling point. It is noteworthy that this alga which was flourishing in July was all dead in November.

The scalding water also oozes through the sand of the adjacent beach in abundance for a distance of at least some hundreds of yards. It is even stated that as far as Ndaku, a mile to the westward, the hot springs issue at intervals through the beach.[22] There are evidently also extensive submarine springs close to the beach; and probably Wilkes was not far from the truth when he remarked that the “whole area of half-a-mile square seems to be covered with hot springs.”

Off the beach, a few hundred yards to the westward of the springs, is a batch of dead reef formed of massive corals and only approachable from the shore at extreme low-tide when it is a little exposed. From numerous small holes and cracks in the dead-coral hot water issues almost at the boiling point (210° F). It is apparent that these springs have appeared at this particular spot since the corals grew. But it is remarkable that this has been apparently going on since the visit of Wilkes in 1840. He refers to a coral rock, distant one-third of a mile from the springs and 150 feet from the beach, through which boiling water was issuing in several places. This rock which was then 10 feet wide and 20 feet long, was at his visit exposed for three feet at low-tide and covered at high-tide.[23]

The geological characters of this locality are described on page 191. I may here remark that if these thermal springs occupy the position of an old crater, it would require much imaginative power to restore it now. The off-lying small island of Nawi might by its situation appear to countenance this idea, but I found no special indication, when I examined it, in support of this view. From the geological character of the district, I would infer that if a crater once existed here it was submarine and that it has been long since obliterated by marine and aërial denudation. The boiling springs come up through apparently a rotten volcanic agglomerate. The slight hollow of three or four feet deep, in which they lie, was considered by Kleinschmidt to be an old crater cavity; but it is only 40 or 50 feet across, and in the earlier descriptions the hollow is described as surrounded by a mound of earth. As shown below, the natives themselves may be held responsible for many changes in the surface around the springs. There is, in fact, no trace of a crateral cavity in this district now.

I will now briefly notice the history of the boiling springs since 1840, when they were visited by Commodore Wilkes. At that time there were five springs, situated in a basin 40 feet across, and possessing a temperature of 200-210° F. Although there was scarcely any appearance of boiling, rapid ebullition could be excited by covering the springs with leaves and grass. The natives alleged that the springs had always been in the same condition. In 1863, when the Chief of Wainunu (Tui Wainunu) came to fight the Savu-savu people, he endeavoured but without success to choke up the springs by heaping earth over them. I was informed of this circumstance by Mr. A. H. Barrack, the owner of the springs. Miss Gordon Cumming also refers to it in her book _At Home in Fiji_. When this lady visited the springs in August, 1876, they were intermittent in their action, the highest making a fountain two to three feet high. According to the description of Kleinschmidt they were in the same intermittent condition in May of the same year. There were then four springs situated in a bowl-shaped hollow. The two larger springs were not constantly bubbling up, but displayed periodic ebullitions of about twenty minutes’ duration, the waters disappearing in the intervals. The other two springs were not then active. Horne, who visited this locality in 1878, refers to three or four principal springs situated in the centre of a hollow, which was surrounded by a mound of earth, the water boiling up to the height of about a foot.

About this time the springs entered for a while into a new phase of action and assumed the form of geysers. According to information received from Mr. A. H. Barrack and other old residents in Savu-savu, the waters spouted up to a height of from 40 to 60 feet, not vertically but at an angle. Each outburst, which lasted for ten or twenty minutes, was followed by a similar interval of repose, during which the springs dried up. This continued for a month or two, after which the springs gradually resumed their normal level. When I visited the springs in July and November, 1898, they were boiling briskly, attaining a height of a few inches, and showed no signs of intermittent action.

I come now to the different analyses that have been made of the water of these thermal springs of Savu-savu. Specimens have been analysed at different times by chemists in various parts of the world, in America, in Germany, in Australia, etc., and the results as far as known to me are now appended.

A. _Analysis by Dr. C. T. Jackson of Boston, U.S., of the water obtained in 1840 by the Wilkes Exploring Expedition._[24]

Specific Gravity 1·0097. Temperature 57° F.

The evaporation of a quantity equal to 1000 grains of distilled water gave 7·2 grains of salt, thus composed:—

Chlorine 3·577 Sodium 1·665 or Soda 2·238. Magnesia 0·440 Lime 0·366 Silica and iron with a trace of phosphate of lime 0·200 Carbonic acid 0·493 ----- 6·741 Organic matter and loss 0·459 ----- 7·200

B. _Analysis by Dr. Oscar Pieper of Hamburg of the water obtained by Mr. Kleinschmidt in May, 1876._[25]

The report stated that the water was clear, neutral in reaction and salt-bitter in taste, brown flakes of hydrated iron oxide occurring in it after long standing. The dissolved salts amounted to “8·48 g. per litre,” and the remark is made that “the concentration is therefore not so great as in sea-water.” The solid constituents consisted in by far the greatest part of Natrium and Calcium chlorides. A quantitative determination, which on account of the small quantity of the water was confined to “eine Chlor und Kalkbestimmung,” gave this result:—

Chlor (Chlorine) 4·79 g. per litre. Kalk (Lime) 2·31 " "

Reckoned as Chlornatrium (Kocksalz) and Chlorcalcium, these results were obtained:—

Chlorcalcium (Calcium chloride) 4·55 g. per litre. Chlornatrium (Sodium chloride) 3·09 " "

Amongst other constituents found in small quantities were Sulphuric acid, Silicic acid (Kieselsäure), Potash, and Iron oxide. Iodine, Bromine, Nitrates, and Borates were completely wanting. “If this water,” says Dr. Pieper, “has healing properties, it does not owe them to its chemical composition.”

C. _Analysis by Mr. H. Rocholl of sample obtained by Mr. H. Stonehewer Cooper probably in 1877 or 1878._[26]

Total solids at 212° F. ·8796 per cent. " " ignited ·7726 " "

The residue consisted of— Free Sulphuric Acid (SO_{3}) ·0049 " " Calcium sulphate ·0260 " " Calcium chloride ·4355 " " Magnesium chloride ·0021 " " Potassium chloride ·0415 " " Water ·1070 " " Sodium chloride ·2641 " " ------- ·8811

D. _Analysis by Prof. Liversidge of the Sydney University of a sample of the water collected by Dr. Bromlow, R.N., about 1879._[27]

The specific gravity was 1·0064 at 60° F. The total solids in solution were 582·4 grains per gallon; but when heated to a dull red heat, the residue was 546·9 grains per gallon, the combined water having been driven off. Iodine and bromine were carefully sought for, but in vain. Four pints of the water were examined.

COMPOSITION.

+--------------------------+------------+-----------------+----------+ | |Per cent. in| Parts per |Grains per| | | residue. |million of water.| gallon. | +--------------------------+------------+-----------------+----------+ |Silica, insoluble | 1·681 | 133·3 | 9·20 | |Silica, soluble | ·074 | 5·8 | ·40 | |Alumina and traces of Iron| | | | | sesquioxide | ·534 | 41·7 | 2·92 | |Aluminium chloride | 1·646 | 128·6 | 9·00 | |Phosphoric acid | traces | traces | traces | |Calcium chloride | 46·754 | 3,652·9 | 255·70 | |Calcium sulphate | 4·770 | 372·7 | 26·09 | |Magnesium chloride | ·154 | 12·0 | ·84 | |Sodium chloride | 42·171 | 3,294·8 | 230·64 | |Potassium chloride | 1·756 | 137·2 | 9·60 | |Carbonic acid | traces | traces | traces | |Loss | ·460 | 34·0 | 2·52 | | +------------+-----------------+----------+ | | 100·000 | 7,813·0 | 546·91 | +--------------------------+------------+-----------------+----------+

Looking at the general character of these thermal springs of Savu-savu we may quote the remarks of Prof. Liversidge and Dr. Pieper that the salts in solution consist for the most part of chlorides, the chlorides of calcium and sodium largely prevailing.

COMPARISON OF THE ANALYSES OF THE WATER OF THE SAVU-SAVU THERMAL SPRINGS, STATED IN GRAINS PER THOUSAND OF WATER.[28]

+----------------+-------+------+-------+--------+-------+-------+------+--------+ | | Date |Chlo- | | |Calcium|Natrium|Total | | | | col- |rine. |Sodium.|Calcium.|chlor- |chlor- |salts.|Density.| | |lected.| | | | ide. | ide. | | | |----------------+-------+------+-------+--------+-------+-------+------+--------+ |Dr. Jackson | 1840 | 3·57 | 1·66 | 0·36 | — | — | 7·20 | 1·009 | |Dr. Pieper | 1876 | 4·79 | — | 2·31 | 4·55 | 3·09 | 8·48 | — | |Mr. Rocholl | 1878 | — | — | — | 4·35 | 2·64 | 8·81 | — | |Prof. Liversidge| 1879 |(4·50)|(1·29) | (1·42) | 3·65 | 3·29 | 7·81 | 1·006 | +----------------+-------+------+-------+--------+-------+-------+------+--------+ |Sea-water, tropics |19·46 | 11·08 | 0·46 | — | — |35·00 | 1·02 | +------------------------+------+-------+--------+-------+-------+------+--------+

It is to be inferred from the above that the quantity of salts in solution remains about the same, the proportion varying only in the four analyses, which extended over a period of forty years, between 7·2 and 8·8 grains per thousand grains of water. This is considerably less than the salts in solution in sea-water, namely 35 grains per thousand. The relative proportions of the salts, excepting those of calcium, do not vary more than we should expect in the case of analyses made by varying methods and probably with a varying degree of exactness.

Dana[29] considered from Dr. Jackson’s analysis that the water of the Savu-savu springs is probably of marine origin; but the absence of bromine and iodine, as especially remarked by Dr. Pieper and Prof. Liversidge does not support this view. We might also expect the proportion of the salts to each other to show a greater similarity to that in sea-water than they do. On the other hand the total volume of water discharged, not only by the springs proper but for several hundred yards along the beach, and also between the tide-marks and beyond, must be far greater than could be supplied by the rainfall of this portion of the Savu-savu peninsula, which is only one and a half to two miles across and 800 feet high. We must look, I think, for the source of these waters in deep subterranean streams or artesian basins that would be fed by the rains precipitated in the mountainous districts where the rainfall amounts to at least 200-300 inches in the year. This matter is further discussed in my general remarks on the hot-springs of this island (page 38).

5. THE HOT SPRINGS NEAR RAVUKA.—These springs rise up in the centre of the breadth of the island about nine miles direct from the coast. They are about 200 feet above the sea and are situated on the Ndrawa branch of the Ndreketi River some two miles below the hamlet of Ravuka. They are on a small scale and ooze through a bed of rounded blocks and pebbles close to the water on the left bank. Their temperature in August, 1898, was 148° F. They are covered by the river when it is swollen by the rains, and very probably other hot-springs issue along the river-bottom. The conditions are not suitable for the formation of deposits.

6. THE HOT SPRINGS OF VUINASANGA.—These thermal springs are also situated in the heart of the island on a tributary of the Ndreketi some three or four miles westward from Va Lili and about 150 feet above the sea. On each bank of the river four or five paces from the water and three or four feet above it, there is a small pool two to four feet wide. In June, 1899, the pool on the right bank had a temperature of 131° F., and that on the left bank of 134°. There were no deposits.

7. THE HOT SPRINGS ON THE SOUTH SIDE OF THE NAWAVI RANGE.—These springs also lie within the borders of the valley of the Ndreketi. They may be “located” by describing them as lying a few miles inland from the north coast fronted by Mathuata Island. I did not visit them and have only learned of them from Mr. Thomson’s Mathuata paper.[30] That gentleman refers to them as two in number and situated at the back of the coast range about four miles inland from the village of Nangumu; but no particulars are given.

8. THE HOT SPRINGS OF VATULOALOA.—These springs lie on the Mathuata Coast in the neighbourhood of Mathuata Island. I have not seen them, but am indebted to Mr. Thomson for the particulars here given, which are taken from his paper above quoted. Mr. Thomson, who discovered them in 1880, named them the “Graçie” springs. They issue below high-water mark at Vatuloaloa, and had a temperature in 1880 of about 140° F. They are said to possess many valuable healing qualities.

9. THE HOT SPRINGS OF NAMBUONU.—These springs are situated on the same part of the Mathuata coast as those of Vatuloaloa above referred to. I learned from Mr. Bulling of Undu Point that they issue from swampy ground half a mile inland. They were discovered accidentally by a Japanese who put his foot into them, the temperature being sufficiently high to scald the feet, but not at the boiling-point, probably about 140° F.

10. THE HOT SPRINGS NEAR TAMBIA.—These extensive springs, situate 1½ to 2 miles inland, and rather under 100 feet above the sea, lie near the Mathuata or north coast of the island, some four miles west of the Wailevu river. They rise up in the midst of level country about a mile from the town of Tambia, and near the village of Ngovungovu. Although situated in the valley of the Tambia river, these springs are not adjacent to the river, and in this respect they differ from nearly all the inland hot springs. The hottest spring bubbles up into a pool 5 or 6 feet across, which had a temperature of 180° F., in March, 1899. Near by is a large deep pool, some 20 feet or more across, with a temperature of 100°. It receives the overflow from the smaller pool, and apparently hot water also bubbles up at the bottom. Around the smaller hottest pool there is a considerable deposit of what is mainly siliceous sinter. It incrusts the stones and also the oyster-shells lying about the pool in quantities, where they have been left by the natives after their contents had been cooked and eaten. Some of the shells are almost decayed away, the sinter for the most part alone remaining.

11. THE HOT SPRINGS OF VANDRANI.—These springs occur in the heart of the island, about 8 miles from the coast in a straight line, and about 270 feet above the sea. This is the greatest elevation, as far as I know, at which a hot spring exists in this island. Here they rise up near the base of the central mountain range, close to the head-waters of the Wailevu river which opens into Lambasa bay. The springs bubble up into a pool, a foot deep, on the left side of the river, four or five paces away from the water’s edge, and scarcely raised above it. They are covered over when the river is in flood. In February, 1899, the temperature recorded by my thermometer was 100° F.; but probably it was a few degrees higher at the bottom of the pool. I noticed no deposits.

12. THE HOT SPRINGS OF NA KAMA ON THE WAILEVU RIVER.—These boiling springs, which are of an extensive character, come up in half-a-dozen places on either bank of the river, and are from 5 to 6 miles inland, and about 90 feet above the sea. They are close to the water, and from 1 to 10 feet above it. The temperature of one small pool, where the water bubbled up briskly, was 204° F. in February, 1899. In another it was 194°. The water was probably at the boiling-point in some cases as it entered the pools, and in the others it could have been only a few degrees below it. The rocks of the district are agglomerates and tuffs. I have no recollection of deposits of any extent around the springs.

13. THE HOT SPRINGS OF VUNIMOLI ON THE LAMBASA RIVER.—A few minutes’ walk from Vunimoli, and about 100 yards from the left bank of the river, these hot springs issue in a place named Vunimbele from the foraminiferous clay rock (soapstone) of the district. They are on the side of a ditch which communicates with the river. The natives have cut out of the soft rock small square basins which receive the waters. The temperature of the hottest spring in August, 1899, was 155° F. That of others was 140°. The conditions are not favourable for the formation of deposits. These springs lie about 8 miles inland and are rather over 100 feet above the sea. They are, however, small and unimportant, and the locality in which they occur is now overgrown with vegetation and not easy to discover.

14. THE HOT SPRINGS OF MBATI-NI-KAMA ON THE NGAWA RIVER.—These springs are situated in the Lambasa district about 7½ miles from the coast, and rather over 100 feet above the sea. They issue copiously from the volcanic agglomerate at a temperature of 161° F. (August, 1899), and are only removed a few paces from the river, and a foot or so above it. Algæ flourish in the water, and siliceous sinter incrusts the rocks.

15. THE HOT SPRING OF NANDONGO ON THE HEAD-WATERS OF THE WAI-NI-KORO RIVER.—A few hundred yards from the village and elevated about 180 feet above the sea there is a small pool in the clay of the river bank, 2 or 3 feet above and close to the water, which in September, 1899, had a temperature of 97° F.

16. THE HOT SPRINGS OF NATUVO ON THE NORTH COAST OF NATEWA BAY.—About a mile east of Mbiagunu and near the village of Natuvo, there are two hot springs of small size which I visited in August, 1899. One that issued on the reef-flat from the coral-rock at a temperature of 136° F. was covered over towards high-tide. The other issued near by at a temperature of 131° from swampy ground a few paces among the trees.

17. THE HOT SPRINGS OF NDAKU-NDAKU ON THE NORTH COAST OF NATEWA BAY.—At this place about 2 miles north of Vuinandi some hot springs rise through the reef-flat, which are only exposed at low tide. At the time of my visit they were covered over by the rising tide. The natives described them as not very hot and like the neighbouring hot springs of Natuvo.

18. THE HOT SPRING OF NAVAKARAVI, NATEWA BAY.—The coast village thus named lies about one and a half miles north of Were-kamba. The hot spring is about a mile inland and not over 30 to 40 feet above the sea. It is reached after traversing a low and often swampy tract. The spring in August, 1899, issued from a little rise at a temperature of 133° Fahr., and formed a rivulet 18 inches across.

19. THE HOT SPRINGS OF VUNISAWANA AT THE HEAD OF NATEWA BAY.—Mr. Horne, who was in this locality in 1878, refers to these springs in his book _A Year in Fiji_. They had at one time, he remarks, a wide reputation for their curative qualities; but the people around became so poor on account of the hospitality that custom compelled them to extend to the numerous visitors that they buried up the springs. Mr. Horne was shown the site at the bottom of a muddy creek. I saw it in 1898. It lies 300 or 400 yards in from the beach and only a few feet above the sea. There were no signs of heat then; but I was told that when the stream close by is very low it sometimes is a little warm.

20. THE HOT SPRING OF NDREKE-NI-WAI ON THE SOUTH COAST OF NATEWA BAY.—This small spring issues between the tide-marks from an old reef-patch close to the shore and is only to be seen at low-water. Its temperature in May, 1898, was 130-135° Fahr.

21. THE HOT SPRING OF WAIKATAKATA ON THE SOUTH COAST OF NATEWA BAY.—This important spring lies about four miles east of the town of Natewa. It issues on a hill-slope about 400 yards from the beach and is some 25 or 30 feet above the sea; but it is so beset by undergrowth that the source is not easy to reach. Boulders and blocks of a basaltic rock lie about on the slope; and it is from under a huge boulder of five or six tons in weight that the spring emerges at a temperature of 148° Fahr. (April, 1898). There is a good volume of water, and a series of bathing pools of varying temperature could be readily made. Unlike most of the inland hot springs, it is not in connection with a stream or river.

22. THE HOT SPRING OF NDEVO ON THE COAST OPPOSITE TO RAMBI.—I did not hear of any spring when in the locality; but I learned afterwards that near a stream on the beach there is a hot spring which is covered at high tide.

23. THE HOT SPRING OF NAVUNI NEAR FAWN HARBOUR.—This small spring is situated in a hilly district in a region where olivine-basalts prevail. I was indebted to Mr. Pickering for showing me its locality. It lies about three-quarters of a mile inland and about 100 feet above the sea. It issues from the volcanic agglomerate a few paces from the right bank of the Navuni stream and five or six feet above its level. In May, 1898, it had a temperature of 112-113° Fahr.

GENERAL REMARKS ON THE HOT SPRINGS

This island is therefore remarkable for the number of its hot springs. In the list given on page 40 I have enumerated 23 localities where they occur; but, as shown below, their number will probably in time be extensively increased.

On referring to the map it will be observed that the distribution of these springs is fairly general over two-thirds or three-fourths of the island. Taking this area at about 1,500 square miles and dividing it into squares with sides of eight miles, we should, if the springs were quite evenly dispersed, find a thermal system in every square. Even amongst the Fijians and among the white residents the number of hot springs will cause surprise. Only those of Savu-savu, Wainunu, Nukumbolo, Mbatini-kama, and Na Kama on the Wailevu river have been up to this time generally known. The reason of this is that most of them are insignificant, and with a temperature far below the boiling-point, and ooze up in unlikely and out-of-the way places, as by the water-side in little visited river-valleys, on the reef-flats of not much frequented coasts, and in swampy situations where they are likely to be overlooked. The natives only recognise as “Na Kama” the boiling or very hot springs; and it was only after much questioning that I could get them to tell me of some unimportant “wai katakata” (hot water) which they deemed to be far beneath my notice. The natives were keenly interested in my botanical and geological investigations; but they considered it to be beneath the dignity of a man who had seen the wonders of Na Savu-savu to spend some time looking for a half-forgotten thermal spring in a swamp. From this cause alone I no doubt failed to find several springs. All the boiling springs and those of very high temperature are probably known; but as is pointed out below it is more than likely that a large number of unimportant springs remain to be discovered in many a deserted inland valley and between the tide-marks along the very extensive reef-bound coasts.

As above remarked the hot springs did not come under my notice in all parts of the island. They are to all appearance wanting in the western or Mbua portion, and also in the Undu portion north of Natewa Bay. Taking the first-named region, it will be noticed that no hot springs are indicated in the map west of the Ndreketi and Wainunu rivers. I made inquiries wherever I went, but with no result. On my writing to Mr. Wittstock, of Mbaulailai, who is well acquainted with the Mbua peninsula, he informed me that if hot springs existed in that part of the island he would probably have known of them. In that portion of the island which ends in Undu Point I could neither discover nor hear of any thermal springs east of Lambasa on the north side, and of Lakemba on the south or Natewa Bay side; nor could Mr. Bulling, who has resided at Undu Point for many years, tell me of any springs in his neighbourhood.

On looking at the general map it will be observed that the hot springs are confined to the area of basic rocks, although they do not occur all over that area, not being indicated in the map to the west of the Ndreketi and Wainunu rivers. They are not known to occur in the region of dacites and acid andesites, as in the case of the Drandramea district; and they have not been found in the area of rhyolitic and trachytic rocks that extends from Undu Point to Mbuthai-sau on the north coast and to near Tawaki on the Natewa Bay side. The region of hot springs would be limited on the east by a line joining the Mbati-ni-kama springs with those of Nandongo on the Wainikoro river and Natuvo on the north shore of Natewa Bay. Such a line, though lying within it, roughly indicates the limit between the regions of basic and acid rocks.

The situation of the hot springs in the lower levels, and their non-discovery at elevations exceeding 300 feet above the sea, are facts of importance. In more than half the cases they arise close to and often on the banks of streams and rivers, occasionally indeed at the river-bottom; and no doubt numerous unknown thermal springs issue under water from the river beds. In about a third of the known cases the springs come up on the coast between the tide-marks, usually rising through the reef-flat. At times even they are to be observed below the low tide level; and one can scarcely doubt that there are a large number of undiscovered springs that are never exposed at the lowest tides. It is also very likely that a number of hot springs issuing between the tide-marks are still to be discovered without much difficulty.

The same may be said of inland hot springs. Looking at the insignificant character of many of them and noting their occurrence in places where they might easily be overlooked, it is highly probable, as before remarked, that a number of springs exist inland, which, though once known to the natives, are now forgotten. The interior of the island is very sparsely inhabited now; but there is evidence of a much more populous condition in old times. The present natives are fast losing the knowledge of the interior of the island which their forefathers possessed; and many tracts in the mountain districts are far removed from existing paths. From the haphazard manner in which I lighted upon thermal springs beside the head-waters of the Ndreketi, Wailevu, and Wai-ni-koro rivers, I cannot doubt that many more exist in similar localities not visited by me.

With regard to the distribution of the springs as respecting temperature, I cannot find any marked arrangement either in their grouping or in the amount of elevation. It is noticeable, however, that the three systems of hottest springs, that of Savu-savu (210°), that of Na Kama on the Wailevu river (204°), and that of Tambia (180°) are all less than 100 feet above the sea. Although the springs of highest temperature are confined generally, with the exception of those of Savu-savu, to the main mass of the island, it would seem that adjacent systems of springs may differ much in temperature. The springs of Vunimoli, for instance, have a maximum temperature of 155°, which is nearly 50° lower than that of Na Kama, three miles to the westward. Hot springs are more numerous in the region around Lambasa than in most other districts. Lastly, I may add that earthquakes are apparently more frequent in the Mbua district, where no thermal springs are known, than in any other part of the island.

With regard to the deposits formed around the springs, it may be observed that the circumstances are not usually suitable for their formation, as for instance when they rise through the reef-flat or in swampy localities. In those springs, however, where the temperature is over 150° F., and where the water spreads over a surface so as to facilitate evaporation, deposits of white sinter associated with algæ occur, as at Savu-savu, Tambia, and Nukumbolo. Its composition varies a little in different localities. At Savu-savu it is compact and laminated and formed almost entirely of hydrated amorphous or colloid silica. At Mbati-ni-kama the siliceous sinter is more friable, with a tendency to form opal. The sinter of the Nukumbolo springs resembles that of Savu-savu; but it also contains a good proportion of carbonate of lime (20 per cent.) in a granular form, and that of Tambia has the same characters. It is not unlikely that this lime is derived from the decayed shells, such as I have referred to in the case of the Tambia springs.... It may be here observed that Mr. Weed and others, who have studied the origin of siliceous sinter in the Yellowstone region and elsewhere, regard it as the secretion of algæ, mosses, &c., that grow in hot waters (_American Journal of Science_, vol. 37, 1889).

I come now to some general considerations respecting the hot springs of Vanua Levu. In the first place there is the singular fact that the inland hot springs nearly always make their appearance along the present lines of surface-drainage. But I do not gather that the hot springs are of more recent origin than the rivers and streams, by the side of which they rise. On the contrary the hot springs are probably far older. The conditions of subterranean drainage that favour the formation of springs at the surface, whether cold or thermal, would no doubt often determine the direction of surface drainage in a newly-formed land. Those familiar with modern volcanoes will recall the absence or rarity of streams and rivers, and the frequency often of cold and thermal springs at and near the coast, which are sometimes of such bulk at the exits that the expression “subterranean river” would be nearly appropriate. The presence of artesian reservoirs may also in some localities be safely assumed. I will here draw a little on my own experience of volcanic regions.

On the lava-bound coasts of the riverless southern portion of the large volcanic island of Hawaii, the subterranean waters issue as cold and thermal springs at numerous localities. At Punaluu, and at Ninoli, a mile to the westward, there are extensive freshwater springs at and near the beach which have a temperature of 64° F. all through the year,[31] those at Ninoli issuing as a large subterranean stream. East of Punaluu and at intervals along the Puna coast, springs of water, sometimes fresh and cold with a temperature occasionally as low as 64°, at other times mineral and thermal, but with a temperature not usually above 95°, issue at the surface or at the bottom of deep fissures in the old lava flows.... In Oahu, another island of the Hawaiian group, where the volcanic forces have been long extinct, artesian wells have been in extensive use for some years in the irrigation of the sugar-cane plantations. The last water-bearing strata are reached at depths of 400 to 500 feet.[32] The subterranean or artesian reservoirs are evidently therefore on a large scale; yet Oahu is scarcely one-third the size of Vanua Levu in Fiji.... Lastly, I will refer to the numerous subterranean streams that issue forth, as cold and thermal springs, from beneath the lavas near and at the Etna coast, as for instance in the vicinity of Acireale. The Etna slopes are in great part deforested, and in consequence soakage is relatively small, and after heavy rains much of the water runs off in the torrents. Whilst in this locality I was impressed with these facts, and I formed the opinion that in ancient times when Etna was well wooded the discharge of subterranean streams at the coast was far greater than at present.

For these reasons and on other grounds, amongst them notably the absence of recent crateral cavities, I infer that the numerous hot springs are the outflows of subterranean streams, fed originally by the “soakage” arising from a rainfall of at least 200 to 300 inches in the mountainous portions of the island. Such subterranean streams run probably at considerable depths, emerging, it is likely, as often under the sea as they do on the land.

Since writing the above I have read in the Journal of the Royal Geographical Society (November 1902), an abstract of a lecture by Prof. Suess on the subject of hot springs and volcanic phenomena. Thermal springs, he holds, are supplied by hypogene waters and do not receive their salts from the sea. Such springs, according to this view, being the survivals of volcanic activity, originate in the depths of the earth’s crust and bring water to the surface for the first time, not deriving it from infiltration. It seems almost impertinent to suggest a view opposed to that of such a high authority; but it appears to me that the frequent situation of the Vanua Levu thermal springs along the lines of surface-drainage requires an explanation that does not altogether exclude the agency of infiltration.

LIST OF THE HOT SPRINGS OF VANUA LEVU, 1898-99.

---------+----------+----------+----------+----------+---------+-------- Locality.| Coast or | Height |Near or |Siliceous |Nature |Tempera- | inland. | above |far from | sinter. |of the |ture. | |sea-level.|streams. | |surface | | | | | |at the | | | | | |exit. | ---------+----------+----------+----------+----------+---------+-------- 1. Wai- |Coast to |Sea-level |River |Little or |Soil-cap,|100°- nunu |four |to 20 or |-side and | none |tuffs, |130° F. |miles |30 feet |under | | &c. | |inland | |water | | | | | | | | | 2. Nato |Three to |50 to 100 |Near |Little or |Soil-cap |110°- -arau and|four |feet |brooks | none | |126° F. vicinity|miles | |and | | | |from coast| |streams | | | | | | | | | 3. Nukum-|Six miles |130 feet |About 100 |Mixed with|Agglomer-|157° F. bolo |inland | |yards | lime |ate-tuff | | | |from | carbonate| | | | |river | | | | | | | | | 4. Savu |Beach and |Sea-level |Inland |In fair |Rotten |208°- -savu |150 yards |to 10 feet|springs | quantity|volcanic |210° F. |inland | |near a | |agglomer-| | | |brook | |ate | | | | | | | 5. Ravuka|Nine |200 feet |River |None |Pebble |148° F. |miles | |-side | |bed | |inland | | | | | | | | | | | 6. Vuina-|Ten miles |150 feet |River |None |Soil-cap |131°- sanga |from | |-side | | |134° F. |north | | | | | |coast | | | | | | | | | | | 7. Foot |Four |Not known |Not known |Not known |Not known|Not of Nawavi|miles | | | | |known. Range |inland | | | | | | | | | | | 8. Vatu- |Coast |_Nil._ | | | |140° F. loaloa |below | | | | | |high-tide | | | | | |mark | | | | | | | | | | | 9. Nambu-|Half-mile |Probably |Not known |Not known |Swampy |140° F. onu |inland |slight | | | |(proba- | | | | | |bly). | | | | | | 10. Tam- |Inland |90 feet |Not near |Abundant |Soil-cap |180° F. bia |one and | |a stream | | | |a-half to | | | | | |two miles| | | | | | | | | | | 11. Vand-|Eight |270 feet |River |None |Old |100° F. rani |miles | |-side | |river-bed| |from | | | | | |coast | | | | | | | | | | | 12. Na |Inland |90 feet |River |Probably |Agglomer-|194°- Kama, |five to | |-side | little |ates and |204° F. Wailevu |six | | | |tuffs | |miles | | | | | | | | | | | 13. Vuni-|Inland |120 feet |About 100 |None |Foramini-|{140° F. moli |eight | |yards | |ferous |{155° F. |miles | |from | |clay-rock| | | |river | | | | | | | | | 14. Mbati|Inland |130 feet |River |In fair |Volcanic |161° F. -ni-kama |seven and | |-side | quantity|agglomer-| |a-half | | | |ate | |miles | | | | | | | | | | | 15. Nan- |Inland |180 feet |River |None |Clay |97° F. dongo |four | |-side | | | |miles | | | | | | | | | | | 16. Nat- |Coast and |_Nil_ | |None |Reef-flat|{131° F. uvo |between |and a few | | |and |{136° F. |the tide- |feet | | |swampy | |marks | | | |ground | | | | | | | 17. Nda- |Between |_Nil_ | |None |Reef-flat|Not ku-ndaku |the tide- | | | | |known. |marks | | | | | | | | | | | 18. Nava-|A mile |30 to 40 |Swampy |None |Soil-cap |133° F. karavi |inland |feet |ground | | | | | | | | | 19. Vuni-|From |A few feet|Near a |Not known |Soil-cap |Not sawana |beach 300 | |brook | | |known. |or 400 | | | | | |yards | | | | | | | | | | | 20. Ndr- |Coast |_Nil_ | |None |Old reef-|130°- eke-ni |between | | | |patch |135° F. -wai |the tide- | | | | | |marks | | | | | | | | | | | 21. Wai- |Inland |25 or 30 |Not near |None |Rises |148° F. katakata |400 yards |feet |a stream | |beneath a| | | | | |boulder | | | | | |of basalt| | | | | | | 22. Ndevo|On coast |_Nil_ |Near a |Not known |Probably |Not |below | |stream | |the |known. |high- | | | |reef-flat| |water | | | | | |level | | | | | | | | | | | 23. Nav- |Inland |100 feet |Near a |Little or |Volcanic |112°- uni |three- | |stream | none |agglomer-|113° F. |quarters | | | |ate | |of a | | | | | |mile | | | | |

Summary of the previous remarks on the hot springs of Vanua Levu.

(1) Hot springs have been recorded from 23 localities, but there are probably many undiscovered or forgotten.

(2) They are distributed over much of the island; but have not been observed in the Mbua or Western end and in the Undu extremity east of Lambasa and Lakemba.

(3) They are confined to the areas of basic rocks and are not known in the districts of dacites and other acid andesites or in those of quartz-porphyry and trachyte.

(4) They are always found at low elevations, never exceeding 300 feet.

(5) Whilst more than half are situated along river and stream courses, nearly all the remainder lie between the tide-marks.

(6) In only two localities is the temperature at or near the boiling-point. In one place it is 180° F., and in most of the other springs it ranges between 100° and 150°.

(7) Siliceous sinter is formed where the temperature is over 150°.

(8) As exemplified by the water of the Savu-savu springs the proportion of salts in solution (8 per 1000) is constant over many years; whilst in this fact and in the relative amounts of each salt there is a sharp distinction from the composition of sea-water.

(9) The hot springs are older than the streams and rivers, along which they are so frequently found.

It would appear that they are largely supplied from the “soakage” of the heavy rainfall in the mountains.