Incandescent insects

In the dark , damp corners of our cities there is a corrupt subcul­ture abroad. It is most active at night, when innocent victims, lured to these retreats by small, bright lights, are captured and murdered. In the same dark enclaves, confident males, often congregating in small gangs, lie in wait to seduce virginal females the moment that they slip out into the cool night air. Where conditions are crowded, there are nightly fights, too, sometimes to the death, and even some cannibalism. Such a scenario would normally warn people to steer well clear of these ghettos of depravity, but they are an attraction that both residents and overseas tourists flock to see. They are not the red-light districts of our cities, but rather areas where the bluish light of bioluminescence brightens the blackness, and the lives and deaths of humble glow­worms play out a nocturnal drama. For decades, the glow-worm grot­tos in limestone caves at Waitomo have been a world-renowned tourist stop, and, more recently, similar caves near Kaitaia and Te Anau have offered the same attraction at the northern and southern ends of the country. To enjoy the dazzling light shows at these remote locations, many visitors travel for hours, little realising that the same creatures can invariably be seen glowing just as brightly close to their own homes. Throughout the country, those who are prepared to venture out in the dark—and who do not dull their night vision with bright torches—can usually find glow-worms if they look in the right places. Alongside streams, in public parks, on damp, south-facing walls  of cuttings, inside abandoned rail­way tunnels and under the seeping roofs of large culverts, the twinkling lights of these insects can commonly be seen. In all of these sites, glow­worms avoid surfaces that are splashed or washed by trickling wa­ter, and they are most abundant where soft mud covers the ground below. Glow-worms are the carnivorous larvae of a gnat, Arachnocampa luminosa. These slender, semi­transparent grubs deserve the atten­tion they get not just for their glow­ing tail-lights, but also for the cun­ning traps that they set to snare their prey. The larvae spend their lives suspended from the undersides of rocky ledges and overarching vegetation, from which they deploy their sticky insect traps. The person who in­vented the adhesive fly-papers that were commonly found hanging from the ceilings of our homes before the days of aerosol fly-sprays could well have been an admirer of glow-worm snares, for both employ the same trapping technique. Each gnat larva lives in a simple tube made from silk and mucus that hangs like a hammock from the ceil­ing above by a number of silken guy ropes. The tube is more than twice as long as the worm-like grub which inhabits it. The worm can slither very quickly from one end to the other to catch prey which has be­come entangled in one of its snares or to retreat from predatory harvestman spiders that are partial to glow-worms. By reaching out of its hammock, the glow-worm can hang an array of silk threads from the ceiling all around it. Unlike spiders, which se­crete silk from a complex set of glands in the abdomen, glow-worms secrete silk from a gland just behind the mouth, and decorate each thread with large beads of sticky mucus. Most glow-worms set out at least a dozen threads, and some have sev­eral dozen hanging down like a crys­tal chandelier around the insect's biological light bulb. Along shaded, overgrown banks the threads are seldom much longer than a couple of centimetres, but in the still air of tunnels and caves, where there is less likelihood of hanging threads being tangled by disturbing breezes, they are frequently up to 20cm long. The threads are aerial fishing lines set to snare the glow-worms' insect prey. The most common items on the glow-worm menu are midges, which seem particularly susceptible to the lure of glow-worm lights. Glow-worms are often found in sites where there is soft, wet mud below, because these mires are the midges' favourite breeding grounds. As adult midges emerge from their pupal cases, their instinct is to fly in search of other wallows to colonise. Setting out under the safety of darkness, it is natural for them to fly up towards a clear starlit sky. It takes very little imagination to realise that this is the false image created by a colony of glow-worms in a cave or tunnel, where a dark background bespeckled with bluish-white points of light could easily be mistaken for a starlit heaven. It turns out to be an adhesive hell. As the midges approach the false stars, they become stuck to the sticky beads of mucus, and then, as they struggle, entangled in the hang­ing lines. A glow-worm moves quickly to the threads that have trapped prey and hauls them up to its tube. With sharp, powerful jaws, it bites into the food and devours it immediately, discarding only the wings and other hard parts of the exoskeleton that it cannot digest. The chemical basis for the glow­worm's glow is not fully understood, but appears to involve a combina­tion of energy (in the form of ATP—the energy "currency" in living cells), magnesium, oxygen and the enzyme luciferase, all co-operating to generate light from a substrate molecule called luciferin. All known bioluminescent insects (per­haps a few dozen to a few hundred species of flies, springtails, bugs and beetles) use some variant of this sys­tem. While some species emit light from their whole bodies, most have specialised light-producing organs. In glow-worms, light is generated by an extension of the Malpighian tu­bules (excretory organs analogous to a mammalian kidney). Some bioluminescent insects (such as fire­flies) are flashers, while others, like the glow-worm, exude a gentle, steady glow. Not all shine with the same hue, either. The glow-worm emission peak is a bluish 488nm, whereas that of the firefly is 547 - 600nm—a more orange light. How many watts does a glow­worm produce? The best estimate obtained during the course of re­search for this story was that each worm is capable of producing one nanowatt (one thousandth of a mil­lionth of a watt). Glow-worms may be ever ready, but they are unlikely to dent the torch market—although, apparently, some people have tried to harness them for this purpose. In a book entitled How We Lived Then, a history of everyday life during World War II, the author noted that a shortage of torch batteries led to a novel solution: "A torchless West Country landgirl recalls finding her way home by the faint glimmer of a handful of glow-worms, placed on the mirror of her handbag." The growth rate of glow-worms is dependent on the availability of food. Hatching from clusters of round eggs laid in moist ceiling de­pressions, the young larvae (which can glow as soon as they emerge) disperse, crawling away to find suit­able vacant sites from which to sus­pend their first feeding traps. Sometimes there is competition for space, and as growing larvae at­tempt to expand the size of their midge traps with more threads, ter­ritorial fights occasionally break out. Reaching half out of their hammock tubes, they strike out at each other while their tail-lights glow brighter as the conflict intensifies. It is not unusual for these disputes to be settled beyond further argument with the victor de­vouring the vanquished. After several months—longer, when food is scarce—a larva reaches pupation size of 35 - 40mm. Before pupat­ing, it gathers in all of the sticky fishing lines that sur­round its tube, presumably in order that it does not become trapped in its own snare when it emerges as a delicate winged adult. Suspended by a single thread from the ceiling, in a transparent skin made from its larval hammock, the pupating glow-worm immedi­ately becomes shorter and plumper, shrinking to about half its length. Over the next fortnight its transfor­mation into a delicate long-winged fly can be observed through the transparent skin that encloses it, and throughout the process the fluores­cent filament in the last segment of the body continues to glow intermit­tently. In females, which are noticeably larger, this light takes on a new func­tion in the darkness as they near the time to emerge as flying adults. Per­haps it would be appropriate at this stage if their flashing neons were red, because they use them una­shamedly to attract recently emerged males. As the males gather around, their attentions cause the mature pupa to glow with even brighter pulses, and when the female eventually breaks out of her cocoon she is mated in­stantly. All this indecent haste is neces­sary, for the females have but a short time to mate, disperse and lay their eggs. Many perish within a day, and none live longer than three days. Their lights are extinguished for the last time as they commence their egg-laying, then die exhausted.

Magazine

016

ISSUE 016

Sep - Dec 1992

Pupu springs

D'urville is.

Glow worms

Country women

Science fairs

Volcanoes

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Living World

Living between mud and heaven

Jan Styles Mangawhai I've never been a city person; always loved the country and animals. I don't think you've got enough time in the city—to just learn about life. I think you've got to learn to exist in the city. You don't learn to do anything else; you don't live, do you? You run from one place to another. Here, I feel I could cope with anything, you know. It's hard work, hard yakker. You go out all weathers because your animals have got to come first, but I find you can cope. It's amazing what you can do. I think you get more time to learn what you're capable of. I love this life. If you want to sit down and watch TV, okay, that's fair enough, that's what you get out of life. But I think if you put more into it, you get more out of it. I enjoy sewing and love knitting. I love my grandkids—two just up the road is mighty handy. I believe in filling every day with love and laughter, and not waste it. They're all God-given days; they're all precious. When my first marriage broke up, I applied for a housekeeping job, and actually Brian answered. I swore I would never get married again—there's the results over there, seven grandchildren now, and one hell of a terrific marriage. We've been together twelve years now. He always says I was the best thing to come out of the paper since fish and chips. We lumped two families together, and it's worked. Farm life makes a family. [Chapter-break] Olivia Spence Port Albert I earned my first wages at twelve, and I from then on you paid five bob a quarter in tax. Looking after my uncle's sheep was the job I had. Go round them every day, every evening. See there were none cast, and pick up any lambs, and see their mothers feed them. Then I was doing housework after that. I was in Land Service for a while—Women's Land Service in the war. A lot of my girlfriends were doing Land Service. We had to wear our uniform if we went out anywhere. After about four or five months, I ripped all the muscles in the side of my leg. I was doing farm work that girls shouldn't be doing, probably. Heavy lifting, I suppose. The day I did it, I was only lifting a cream can, which I'd been doing year in, year out. It was heavier than the one we had at home, but still, it was only a cream can. I just lifted it wrong, I suppose, or slipped or something. During the war I was all over the place. I went to the South Island—actually that was in '47, that was after the war. Moved down for apple packing, Motueka. Lived at the hostel, and went out tobacco tying in the weekends. Some of them went hop picking, but that was awful; it ripped the hands to bits. I was involved with the Country Women's Institute sixty years. I'm still involved, but I don't do much nowadays. I just go to the meetings, that's all I do now. I joined at Marareti, which is about six miles from Paparoa, when I was nearly fifteen. There was nothing much else in those days—you played tennis, you played basketball, and went to dances in the truck. Incidentally, I'll be seventy-five tomorrow. We bought our house twenty-four years ago. Part of it was the old Post Office. Those couple of sheep's all we got now, and the dog and the cat. We don't like the towns, I suppose. Don't like the town life. I haven't got any children. He's got a daughter from his first marriage. But I didn't have any. [Chapter-break] Michelle Moir Michelle Moir grew up on a dairy farm in Northland, surrounded by strong, capable women. When she left her Whangaripo Valley home for Auckland, Moir realised that while a new life was beginning for her, she had also been separated from the strong web of her community and the influence of the women who had always been part of her daily life—"women who are straight up and always friendly". As part of her studies at Elam School of Fine Arts, University of Auckland, Moir returned home to capture and record "the spirit and dignity of country women"—women "whose voices and faces are often unheard and unseen, their lifestyle unknown to many city people." Throughout 1990 and 1991 Moir photographed 80 Northland country women. "First I began photographing women I knew," she says, "and then the work grew through word of mouth. Each woman would in turn refer me on to others. "Country women don't mix with large numbers of people much of the time, and I think that this isolation shapes them. Many say they have been quite lonely at times, living in the country, especially when they had small children. But gradually they learn to live with their own company. And something about that process, and having to think in terms of seasons and practical matters, makes them strong. "In this work I'm seeking to promote an understanding and appreciation of the diversity of the women who are distinctly New Zealand's country women." [Chapter-break] Mary Ashby Oruawharo Well, we had a bullrush house we lived in back here. You get these raupo and tie them in bundles and you throw them over the roof, so the rain don't go through. And the rain don't go through. It's amazing, that. You always think it might leak, eh? There was fourteen of us from different families. Our parents were all brothers and sisters. They were all working so we had to stay with Grandma so we could go to school. My great-grandmother was a hundred and four and my grandmother was eighty. Anyhow, these two old ladies looked after us, and they had huge gardens, miles of it. They dug it by hand, planted kumara, corn. I went to school, but the thing is, 1 never ever learnt to read or write, for the simple reason that I was probably the smallest at the time. So if I caught the horse then I could go, but if I didn't catch the horse then it was too bad for me, I couldn't walk that far. A habit of Grandma's was prayer. When you sit down you've got to have prayers, and grace for meals. Early hours of the morning it's still dark and we're sleeping all on the floor together and Grand­ma's sitting like that in the dark—no light, no nothing—and she wants us up. She says, 'Are you up?'—`Yes', and I'm still under the blankets or under the bag, and she says, 'Are you sitting up?'—`Yes', and nobody's sitting up. They're all still underneath, and she couldn't see because it was still dark. Then she says the prayers, for, oh, I don't know how long. Sometimes I think I must have gone to sleep, and when I woke up she was still going. Then you'd come in for breakfast again and say grace, finish grace, 'All ready to go to school?'—`Yeah'—`Got lunch?'—`Yeah'—`Okay, stand in a row, stand in a row', and every one of us has to say a prayer before we leave. I just know if I don't say it I don't know what's going to happen. Sometimes I just want to say it as I'm laying down, and I know it's not right unless I sit up, sit up and say it properly. So now, this is good, this is good. You've got a car, you've got hot water, you've got cold water, and I feel sad 'cause my parents didn't have it, you know. [Chapter-break] Coral clinton Wells Ford We had twelve in my family, but three of my brothers died when I was little. They were older than me—I'm the youngest. But there was nine of us that lived, although they're mostly all clonked out now. Out of nine, l've only got two brothers and a sister left. Sad. I was the afterthought. Because of my sisters' ages they had babies when I was born, so there's a lot of them about my age. My dad was a very comical man and even ourselves, you know, we could come up with anything quite quickly. My father had a farm at Pakiri. Poor old Dad, he really had to struggle. I don't ever remember being rich but I don't ever remember being unhappy or having worries or anything. I suppose he did all the worrying. I'll always recall when we moved to Auckland. My Mum was elderly and she needed care and what she had was asthma. We had an old auntie came and lived with us when Dad died. That was Mum's sister, and she had gangrene and then they had to cut her leg off, so we had to move to Auckland. I had to go, I was the only one able to look after them. I was seventeen. Didn't really like it either—hated it, used to get homesick really hard. In Pakiri when the Power Board came around, and it was morning tea time, you gave them morn­ing tea. I worked at the factory across the road so I used to come home at lunchtime to Mum and Aunty. I can remember coming home one day and the chimney sweeper and the Power Board was there. And here's Mum, flat out. She's made some scones, she's got the chimney sweeper sitting at the table. She's yelling out, to the Power Board. I said, 'Mum, you don't do that, you don't go asking people in off the street like that'. She said, `You just be quiet there, they want a feed as well as anybody'. That was the way country life was. It's influenced me, and I'm still like that. I think that a lot of the trouble today is people don't care and it doesn't cost you nothing to care. It doesn't cost you a dime. [Chapter-break] Joanna Roberts Mangawhai "Twenty-five years we've been here. I sound like a real old woman now, but when we came here, everybody knew about us before we arrived, because not very many farms changed hands in the area. Malcolm and I were just newly-weds, too. We'd only been married a few months, plus we had a sports car as well. We had a little convertible MG sports car. Now why did we sell it? Oh, I got pregnant with Guy, that's right, and it was rather difficult to get in behind the steering wheel. I had to learn to adapt, coming to the North, I have to say. Being brought up in the Hawkes Bay, the Hawkes Bay has a set of values, a social system which is very strong. I used to have to ask my girlfriends, if they were coming to stay with me, which way they held their knife and fork. Because if they held their knife the way my mother deemed to be the 'common' way, there would be a scene at the table. So I used to ask them beforehand 'Could you see if you could hold it, you know, like this?' Now here was I, in the North. I usually had my string of pearls on, 'cause I can't throw away that Hawkes Bay identity, you see. I didn't fit into any of the categories. always been very extroverted—some people would say I'm a very over-the-top woman. I don't suffer fools, and I've always assumed that I can do whatever I want to do. And it doesn't matter whether I'm a woman—I'm the one who's out on the road all the time with my newspaper reporting and council work and things like that, and Malcolm's ending up putting more time into the animals. We've just got seventeen acres. It was originally just one of the paddocks on his family's farm. I'm now able to indulge in my donkeys. Donkeys are a bit like a childhood fantasy, really. Everybody loves donkeys. Once we got one I got hooked on them, and so we've got five now. And I've been the president of the Donkey Society in New Zealand." [Chapter-Break] Jill Parsons Mangawhai I was born in Napier, and grew up on an apricot orchard. My oldest brother was farming up here, and I thought I'd come up here for a change. I was working in the bank, and I used to go out and see him in the weekends, and went to a dance one time and met Eric. I didn't know either end of a cow.I was born in Napier, and grew up on an apricot orchard. My oldest brother was farming up I used to go over and wash the yard down, but gradually got more and more involved as I got more confident. It's all dairy. In the calving time there's a lot of work and a lot of stress, getting them through mating. You've got your calving—it starts on the nineteenth of July—and then you've got your mating which starts on the tenth of October. You've got to watch for the heat signs—it's only every twenty-one days in cows. Otherwise you've got to wait for another cycle. If you don't get a condensed calving pattern and don't get most of your herd calving in that first three to four weeks, then you're getting less milk. I think it's a close-knit community. I've been going to Garden Club. We take our best blooms, our best cluster, a vege, a fruit, and an arrangement. We have a special flower for each month. The next meeting is three single blooms, three pieces of silverbeet, and a mandarin and a dried flower. Our farm discussion group—we meet on the fourth Wednesday of each month—we go to someone's farm and cover a subject. Last Wednesday it was kikuyu; next month, cow condition. Last year we had a progressive dinner while the cows were out. We started at one place and had chips and dip and a drink, then on up the road and had soup, and up the road again and had fish, then up the road again we had dessert, then up the road for coffee, and all went home about midnight. Table tennis—I've been in it since we've been here. Last Tuesday night two of the young boys beat me, but I'm quite happy to see them—gives them a thrill. Told them it was my off night. I'll get back at them next week. [Chapter-Break] Doreen Gallie Mangavuhai I worked in a shop for a little while, and then on to a factory making plastic inflatable toys and things like that. Basically that's where I stayed until I got married. Then I came here—spent the next twenty-two years here. Milking and raising a family of five girls. I found most people around here were a lot older than me—my mother's generation. When we first came here I couldn't drive, and that limited me a bit. I had no children, so there were no experiences that I could relate to, and I was a city person. I was a shy person at that stage. I could go to a Plunket meeting, after the children were born, and say nothing all night. I'd sit and listen, and I'd be thinking some of the things that somebody else would say, but I wouldn't have the cour­age to say it. They might have thought I was a bit of a snob or something, I think. I gradually changed, I think, and got used to the farm. I work the morning with Lindsay, fencing, drenching, whatever. For the last three years I've run the farm on my own, because Lindsay's worked off the farm for other people. We needed the extra money to keep the farm going, so he got another job milking for somebody else. It's tiring, very hard sometimes, especially at calving time. But, you know, I succeeded for three years. I wouldn't like to do it for a lifetime. I'd much rather be home with the kids. I can see the differences between my children and children who live in Auckland. When the city ones come up here they are sort of horrified at our kids, out in the muck. I think I prefer them to take their time and grow up. They have to grow up too fast in cities. [Chapter-Break] Mary Frost Port Albert Nick always wanted to be a huntsman, and when he got the job up here we had to buy a property in the area of the hunt. I've always had horses, and can't think of anything worse than to have to travel to your horses. This farm used to be a dairy farm, but it's been chopped up. We're living in the woolshed till the new house is built. We came here and scrubbed it up two years ago. There's no running water, so if we want a bath we have to boil hot water on the stove. I do a lot of work from home—sewing saddle and show blan­kets. Some time I'll have a garden again, I shall have a wonderful garden again. I really can't think of any disadvantages out here. Okay, you can't dash down to the dairy for a pint of milk, but you always have a bag of powdered milk in the cupboard. And the fisherman next door feeds all our cats. The traffic just drives me mad when I go to Auckland. It takes me a week to recover. [Chapter-Break] Sarah Watts LEIGH It was new land that my parents went on to at Pakiri. Even I had a slasher that was my own, but it was blunt—my dad wouldn't sharpen it in case I cut myself. But that's the way I was brought up, to do your share. Carried the cream can right across the creek, and then again at night, when I came back from school. I milked before I went to school. I did that, or breakfast—whatever had to be done. Later, I was involved in working on our farm. My husband and I did it together. I didn't stay home and play ladies when our children were born. We used to take them in the pram, and go back and check every now and again. When they got a bit older the children played in the trees, and we built a pen on the back of the tractor so we could take our youngest daughter. One by one our children left, and that left us on our own again. We moved here to Leigh more or less to retire. But instead of taking up fishing in a sort of fashion, we really got into it. So I worked with my husband on the boat as a deck hand. It was only last year that I gave it up. The flax work is a skill that my grandma taught me. We cared for her, we had her for about twenty years back on the farm. She spent a lot of time weaving, doing the garden. She helped me a lot when I was younger, bringing up the children. This is why I wanted to care for her when she got older. I used to sell my kete in the CML Mall in Auck­land in Queen Street. The late Mrs Greenwood and I, we used to do it when we had time, and before we realised it we would have twenty or so done, and we'd have one day in Auckland. We'd take them up and buy a few things that we couldn't buy before. We used to do that once a month: have a trip, shout ourselves out to dinner. I have four children, and I love them dearly. My eldest daughter is in Telecom in Karangahape Road. My son is a fisherman, and my other daughter is a nurse in Tokanui Hospital, and my other daughter is working in the oyster farm in Mahurangi where she holds the record for opening oysters. I believe in honesty, because when that comes all the other things happen. [Chapter-Break] Toni Smith Or Uawharo I am forty two. I can remember the first day I started at Elam Art School—seventeen I was. I finished with a C pass for painting, and then I had other mucky jobs: car cleaning at Farnsworths, and restaurants. It wasn't encouraged for girls to carry on. I think it was assumed that you would be dropping it soon, that it was a bit of a hobby. I had been encouraged to think that you got carried away by a prince or something. I got married in my second year and ran the Elam coffee bar. It was the only way I was going to be able to leave home—I was too scared. But that marriage didn't last. About twenty-nine I was pregnant. Then we moved away from Auckland to find somewhere in the country. With the baby it didn't feel right that we were living right in town by the Town Hall in Auckland. It was just a desperate move for me to get my wits together, really, and be somewhere more peaceful, more quiet. We'd lived all our lives in Auckland, being party people. Really, I needed a big lie down. I'm a Smith, and that's what I use, and we never did get married anyway. We felt that we couldn't do it a second time, both of us. But we stopped having two different names on the letter box, because there's a lot of religious people and they don't like it, can't cope. There's something like seventeen different versions of Christianity between Waipu and Warkworth. Doing art for money, it just didn't gel in my head. You can't progress if you're always fulfilling other people's expectations. You see this abstract stuff. It probably won't sell locally. People just can't buy it. If they are rich they are elderly and they want a pohutukawa and sunsets. I can do occasional wheeling and dealing here though. I can swap for meat or fish or something for my art. [Chapter-Break] Heather George Mangawhai I just got engaged last night. Well, we've been thinking about it for a while, we've known each other for a long time. We met over a year ago now, through the Young Farmers group. He's from Kaiwaka. When I left school, I knew I couldn't do anything sitting inside, so it would have to be outdoor work. I'm almost nineteen. If I hadn't got this job I would have had to go to a factory to work in. This year there's hardly any farm jobs because payout's gone down, and people that did have farm workers haven't got them any more and their wives are going back into the shed, so there's been hardly any jobs. Seeing there's so few jobs, people are going to take boys over girls because they can do a bit more. I've found that the case so far. My first boss at Kaiwaka, he was a bit wary 'cause I'm not as strong as the males. But everyone's got to learn patience, I've got more than the guys. The last guy I worked for, when I was home, treated me like a boy, not a girl. I did about everything. People are starting to come out of their shells that females can do it—it's getting better. I can't stand knocking calves on the head though, putting them down. Can't stand that job. I've got out of it so far. I've  seen it done plenty of times, but I won't do it. There's not much to do in the way of social activities living in the country. Normally the Young Farmers Club will find something to do like car rallies and barbe­cues, and going to the beach in summer, but we go up to Whangarei for the pictures quite often, ten-pin bowling, hot pools down at Waiwera. We're going to give Auckland a go-over when we go down there. One day.

Geography

Underwater gardens of Pupu Springs

Imagine an underground  reservoir so large that it has its own tides. A spring of such clarity that the term "crystal clear" is actual, not im­aginary. Where distance is decep­tive, and divers in its waters seem to hang suspended, as if in space. There is such a place: Pupu Springs, source of the clearest natural water in the country, lying five miles west of the township of Takaka in Golden Bay.

Volcanic Auckland

I am standing at  the edge of a vol­canic crater, just a careless step away from plunging fifty metres into a lake of incandescent orange lava that boils and hisses. The crater punctures the top of Pu`u 0`o, a cone that sits like a boil on the flanks of its great volcanic parent, Kilauea, on the Big Island of Hawaii. From 1983 to 1986 Pint 0`o was the site of thundering lava fountains which rattled window panes 15km away in the appropriately named village of Volcano. Those and more recent eruptions fed lava flows which have engulfed over 40 square kilometres of the surrounding land­scape. Fall-out from the lava fountains built Pu`u 0`o up to a height of 255m, but at times it seemed as if the fiery convulsions would rip the mountain apart. Comparatively quiet now, the lava still sounds like muffled ocean waves crashing on to cliffs. Acidic yellow fumes spiral up from the lava lake, leaving sulphurous shad­ows on the blackened land that stretches away on all sides. Watching this spectacle reminds me that this is how much of Auckland's landscape once appeared, for Pu`u 0`o is a living relative of the volcanoes which have shaped Auck­land, and helps to tell the story of what those volcanoes were once like. It also serves as a warning of what will almost certainly happen again in New Zealand's largest city. Auckland truly is a city of volca­noes. Climb any one of its volcanic peaks and you can see at least half a dozen more floating above the sub­urban sprawl like green bubbles. Scattered among these landmarks are many less conspicuous cones, and some volcanic sites which are not cones at all—a number of erup­tions simply blasted a hole in the earth's surface, leaving a broad cra­ter with its contents strewn in a thin mantle over the surrounding topog­raphy. Auckland's volcanoes are all rela­tively small, but what they lack in size they make up for in number. There are no fewer than 48 within a 20km radius of central Auckland. They are spread from the dark wa­ters of Lake Pupuke in the north to the quarried stump of McLaughlin's Mountain (Matukutureia) at Wiri in the south. On average, only 3km separates one volcano from the next, and together they comprise the Auckland Volcanic Field. The largest of the volcanoes is the youngest. Rangitoto, its handsome symmetrical form now almost em­blematic of Auckland, took its place as sentinel of Waitemata Harbour only 600 years ago. Its arrival was certain to have been witnessed by the Maori, whose footprints, hearths and food scraps are preserved under layers of Rangitoto ash on the neighbouring island of Motutapu. Until recently, most geologists considered that outbursts from the Auckland Volcanic Field have oc­curred sporadically for the last 100,000 years. However, a new study at the University of Auckland, using the technique of thermoluminescence dating, has es­timated that rock samples from the Pupuke volcano are up to 141,000 (+1- 10,000) years old. Thermoluminescence dating is based on the fact that low levels of radioactivity which are naturally present in rocks cause electrons to move about, and eventually to be­come trapped in defects in mineral crystals within those rocks. When rock samples are heated, the trapped electrons are released, emitting a pulse of light. The intensity of the emission is a measure of how long the crystals have been accumulating electrons, and from this data the age of the rocks can be estimated. Like all dating techniques, the method has inherent uncertainties, and geologists do not yet know how reliable it is for Auckland's volcanic rocks. Most Aucklanders probably avoid wondering too much about the go­ings on in the infernal kitchen be­neath their feet. Far better to worry about what's cooking for dinner than what's cooking, and perhaps ready to boil over, under your own back yard. The earth's interior has been hot since the planet began to form an estimated 4.7 billion years ago. At that time, masses of swirl­ing gas and dust were ac­cumulating into a dense sphere. High temperatures were generated by the col­lisions of impacting mate­rial as the primordial earth grew. Later, gravitational compression of the newly formed planet produced more heat, and the earth's temperature increased still further as it differentiated into layers. Heavy iron sank to form the core, and lighter materials rose upward to settle in layers near the surface. Radioactive decay helps to main­tain the earth's high internal tem­perature, but, while the core remains extremely hot, the earth is thought to be slowly cooling down—losing heat towards the surface, mostly by convection. The earth's solid outer shell, called the lithosphere, is made up of two layers, the crust on top and the upper mantle beneath. These layers are made up of relatively lightweight material which floats on yet another layer called the asthenosphere. This layer usually extends from about 50km to 250km below the surface. It is very hot, and plastic flow of the rock within it allows the lithosphere above to move over it. The lithosphere is not one con­tinuous shell, but is divided into atleast 15 giant sections called tectonic plates that slowly move about, jostling and bumping at the edges. When two tectonic plates collide, one often subducts or dives under the other and into the asthenosphere. Here the high temperatures melt the surface rock which, being less dense, may then ascend again to erupt as volcanoes. This is one way that much of the world's volcanism is generated, especially along the edges of continents. For example, the minefield of vol­canoes in the central North Is­land, which forms the New Zealand portion of the "Pa­cific rim of fire" was laid by the Pacific plate subducting the Indian-Australian plate (see Earth, fire and water, Issue 7). Similar circumstances 15-20 mil­lion years ago gave rise to the Coromandel and Waitakere Ranges. Although within sight of the Auck­land Volcanic Field, these volcanoes are long extinct and are geologically separate from it. At the time of their eruption, the Auckland area was sub­merged in a deep marine trough. Over millennia, sediments settled out from the sea, and debris ava­lanches flowed down the sub­marine slopes of the island volcanoes. The sediments piled up as layers of sand and mud on the seabed. Com­pressed, hardened and raised from the sea, those sediments form much of the present landscape around Auckland's volcanoes. The Auckland Volcanic Field, some 400km from the edge of the Indian-Australian plate, is considered to be un­related to the volcanic activ­ity which occurs at a plate boundary. Instead, the volca­noes are spawned from what geolo­gists call a hot spot"—an extra-hot zone about 100km below the city, near the boundary of lithosphere and asthenosphere. This subterranean oven, which is thought to be fuelled from plumes of hot material rising from deep within the lower mantle, causes partial melting of the upper mantle. The molten rock or magma rises from there up through the denser sur­rounding rocks to form a plume or diapir. When enough magma forms, it can break away and rise all the way to the surface, much like a blob of oil in a bottle of salad dressing. The type of magma that feeds Auckland's volcanoes is known as basalt. It has a high melting tem­perature and is very fluid, so it rises fast, perhaps making the trip within a week. It usually cools to a hard, dark, fine-grained crystalline rock. Much of what sci­entists know about the nature of basalt volca­noes has come from the close study of Hawaiian volcanoes, especially Kilauea, which erupts frequently. There, a very large and prolific hot spot has existed for as long as 80 million years. While the Hawaiian hot spot has remained more or less stationary, the Pacific plate has moved slowly across it, collecting a trail of volcanoes on its surface. They extend nearly 6000km from the newest Hawaiian vol­canoes like Kilauea in the southeast to the eroded Em­peror seamounts in the north­west. Auckland's hot spot is very small in comparison, and its vol­canoes are termed monogenetic because each one results from a single, separate batch of magma. The Auckland Volcanic Field is part of the Auckland Volcanic Prov­ince, which includes two other vol­canic fields further south: one near Pukekohe and Tuakau, and the other south of the Waikato River mouth at Ngatutura. Those volcanoes were ac­tive from roughly 2 million to 0.5 million years ago, and could have been spawned from the same hot spot which has since moved north­ward. Another area with recent basalt volcanoes very similar to those in Auckland is the Northland Volcanic Province, which has been active from over 2 million years ago near Whangarei, to 1300 years ago be­tween Kaikohe and the Bay of Is­lands. [Chapter-Break] For the 100,000-plus years that Auckland's volcanoes have been bursting on to the scene, the surrounding landscape has been in a state of constant flux—mostly the result of changes in global climate. For example, for most of the last 120,000 years the sea level has not been as high as it is now. The familiar harbours surrounding the city were instead the "Manukau" and "Waitemata" Rivers. Several of the volcanoes which are now har­bour inlets (Orakei Basin, Panmure Basin) or islands (Puketutu) actually erupted on to dry land. As climate changed, so did the prevailing vegetation. At times, Auckland was swathed in luxuriant forest like that of present-day Northland. In the warmest periods, stately kauri, attended by great rimu, rata, totara, and kahikatea, were to be found tower­ing above ranks of broadleaf trees through­out the isthmus. Moa probably stalked the for­est floor, cropping the un­dergrowth. In cooler epochs, forest types now found in the South Island probably re‑placed those that preferred more tropical climes. Around 20,000 years ago, scattered beech forest amidst grass and scrublands reigned around Auckland. Sea levels were at their lowest then, so terrestrial vegetation could spread across the harbours and even out past Great Barrier Is­land on the floor of what is now the Hauraki Gulf. The changing mosaic of veg­etation was complicated further by the volcanoes that periodically ruptured the landscape, leaving blackened scars smoking amidst the verdure. After a slow reinvasion, much like what can now be seen on Rangitoto, forest would eventually thrive again on the new soils of the fresh volcanic land. Rock forest with puriri, titoki, mahoe and puka eventually devel­oped on the volcanic cones. Al­though it has been altered by resi­dential properties, the forest on the eastern slopes of Mount Eden (Maungawhau) is the last surviving example of this original volcanic vegetation. Volcanic destruction sometimes served to preserve a record of these ancient forests. At Ihumatao, north of Auckland International Airport, a forest was caught and buried by tuff from the Maungataketake volcano about 27,000 years ago. The forest has since been excavated by wave action from the Manukau Harbour. There in the mudflats lie the re­mains of huge kauri, and other tree trunks still stand upright in the eroding cliffs. Forest was recorded in a different way at Takapuna Beach. There, an ancient forest was engulfed by Pupuke lava flows which sur­rounded trees, then solidified before the trunks burned away. The result is a ghost forest of "lava tree" stumps and tree moulds that you can stroll through at low tide. Nearby, at Thorne Bay, a 2m-diameter kauri tree and other forest debris have left burnt impressions in the solid rock. [Chapter-Break] Charming little Brown's Island (Motukorea) is in many ways typical of Auckland's volca­noes. Today, it is a collection of bright green, curvaceous hillocks, bathed by the dappled blue and teal waters of the Waitemata Harbour. Several thousand years ago—geolo­gists' estimates vary from 30,000 to 8000 years—it was the site of a vio­lent eruption brought about by a batch of 1200°C magma squeezing upwards from thehot spot below. If the later date is accepted, the eruption would have thrust Motukorea into the waters of a shal­lower version of today's Waitemata Harbour, in the manner described below. (An eruption 30,000 years ago would put the volcano on dry land.) When the rising magma reached groundwater buried deep in the lay­ers of sedimentary rock beneath the harbour, the water flashed to steam causing a huge build-up of pressure. The pressure soon became too great to be contained by the surrounding rocks, and a violent phreato-mag­matic explosion tore through the earth's surface. In the ensuing paroxysms, hot, shattered lava and sedimentary rock was blasted high into the air from the volcano's throat. A dirty mush­room cloud of steam and volcanic gases laced with bolts of lightning towered above the harbour. At its base, white clouds billowed out­wards as water pouring into the vent boiled to steam. Many explosions in rapid succession sent out waves which churned the calm waters of the harbour into a frenzied mael­strom. Expanding steam, caught within the rocks thrown from the volcano, disintegrated them into fine dust and gravel. As the eruption contin­ued, saturated ejecta falling back down jetted horizontally outwards (like the shock wave from an atomic explosion), forming a basal surge around the vent. Larger pieces of rock shot out from the volcano to splash into the sea or be caught up in the surges of finer material. Many chaotic eruptions pulsated and rocked the adjoining vents which formed over the next few days or weeks, as the supply of magma and water varied. Successive blasts of pulverised rock called tuff (with the consistency of wet con­crete) built a low rim of consolidated ejecta extending up to 1km away. This crescent-shaped ridge or tuff ring is now prominent on the east side of the island where it grew most. Among the shattered sedimen­tary rock which was redeposited in the tuff ring, there is also fragmented basalt and larger chunks of rock that were caught in the frenzied surges. Fossil seashells, torn from their rest­ing place under the harbour bed by the blasts, are also visible. As the eruption continued, sea water was excluded by the tuff ring, and the aquifer either dried out or was sealed off by solidified magma. The explosions became fewer and less violent as the source of steam diminished, and the volcano entered a new phase in its growth. Driven by rapidly expanding gases in the magma, lava flows and Strombolian lava fountains replaced the phreatomagmatic eruptions. Lava is the term for magma once it has reached the surface. Named for the Italian volcano Stromboli, Strombolian lava fountains pulsate with frequent small explosions throwing frothy lava fragments from the vent. Rough, solidified pieces of this lava froth are called scoria, and are riddled with gas bubbles. Scoria piled up around several small vents on Brown's Island to build scoria cones. When fountaining was pro­fuse, lava sometimes stayed molten, and continued to flow upon land­ing. At other times, degassed lava poured gently from the vents with­out fountaining. In some places, lava flows breached the cones, carrying scoria away with them, and leaving horse­shoe-shaped cone remnants. In the last stages of eruption the summit cone with its elegant crater was built, smothering some of the smaller, earlier cones. Perhaps only a few weeks after its boisterous arrival at the surface, the batch of magma ran out. There stood a brand new island, blackened and steaming in the middle of the har­bour. [Chapter-Break] The presence of  groundwater or surface water (such as the sea) in the path of rising magma was a major factor affecting the evolution of Auckland's volca­noes. If the eruption site was "wet" the volcanoes got off to an explosive start. The resulting phreatomag­matic eruption left a wide crater sur­rounded by a more or less circular tuff ring. Such volcanic craters, called maars, usually formed in low-lying areas where the rocks were saturated with water. Several of the volcanoes, including Panmure Ba­sin, Lake Pupuke, Onepoto, Orakei Basin and Pukaki got no further than this. Most of the debris erupted from a maar is not of volcanic composi­tion at all. Rather, it is "country rock", the rock already present be­fore magma intruded. Not all phreatomagmatic erup­tions let rip in low-lying areas. The most explosive of all Auckland's volcanoes, Three Kings (Te Tatua-a­Riukiuta), must have encountered a large aquifer in the ridge where it erupted. It started with multiple phreatomagmatic blasts followed by lava effusion that filled the craters it had just excavated. If it had happened today, the fall­out from this centre would have thickly blanketed houses and streets within an egg-shaped area more than 6km across from Mount Roskill to Remuera. Close to the vent, every­thing would have been flattened and buried by tuff up to 50m deep. Later, lava fountaining built the three "kings" and several other scoria cones. A lava flow from the volcano flowed 10km to the banks of the ancestral "Waitemata River". (Now that the sea level is higher once again, that flow forms Te Tokaroa, or Meola, Reef, and nearly bridges the Waitemata Harbour.) Apart from the presence of water, the violence of eruptions is deter­mined by the fluidity and gas con­tent of magma. Gas-rich and viscous rhyolite magma, near one end of the fluidity scale, can produce cataclys­mic eruptions, burying thousands of square kilometres in pumice and ash. Eruptions of Lake Taupo, the last about 1800 years ago, were of this sort. Auckland's basalt magma is fluid and relatively gas-poor. Rapid and continuous discharge of this sort of magma is known as Hawaiian-style lava fountaining. Spraying a hail of small incandescent fragments, it produces gravel-like deposits called basalt lapilli. Strombolian lava fountaining, like that at Brown's Is­land, occurs when there is less gas and the lava is more viscous—but not as viscous as silica-rich rhyolite magma. Deposits from both types of eruption contribute to Auckland's scoria cones. Some volcanoes, like the Domain and Mount Richmond (Otahuhu), managed a bit of fountaining activ­ity and are left with tiny scoria cones within a maar. A few, including the now quarried Little Rangitoto (Maungarahiri), in Remuera, had no initial explosive upheaval. They erupted only a minor scoria cone fol­lowed by some lava. Others accu­mulated large cones or combinations of cones which have become promi­nent landmarks in the city. Mount Wellington (Maungarei) is the larg­est individual scoria cone (8.5 mil­lion cubic metres). The cone stands astride a low tuff ring. One Tree Hill (Maungakiekie) is one of Auckland's most complex centres. While building a cluster of scoria cones, it produced lava in profusion. An estimated 260 million cubic metres of lava spread north as far as the Domain, and south nearly to what was then the "Manukau River". The flow of lava from One Tree Hill was so great that two of the cra­ters were never able to form com­plete circular scoria cones. As the erupted scoria fell, it was immedi­ately swept away by the fiery tor­rent, and the cones remained horseshoe-shaped.The cones of Mount Hobson (Remuera), Mount Victoria (Takarunga) and Mangere Mountain, by contrast, were breached late in their eruptions by similar outpour­ings of lava. Lava flows issued from 30 of Auckland's volcanoes. They poured downhill into valleys, sometimes overflowing them and completely masking the earlier topography. Rangitoto's gentle lower slopes were created by outpourings of lava from the crater and flanks of the central cone. Most of Auckland's volcanoes formed within a short time, prob­ably taking up to a few years—though it is entirely possible that even a Mount Eden-sized cone could have formed in a matter of days. [Chapter-Break] Subterranean tunnels  con­nect Auckland's volcanic peaks? Are alien monsters using the network in a heinous plot to destroy the planet? Maurice Gee wrote of such possibilities in his book Under the Mountain, which screened as a television series in 1981. Fantasy, certainly, but within its lava flows Auckland has the next best thing: lava tubes. Lava tubes are the arteries that supply a lava flow. Liquid lava flow­ing from a volcano rapidly forms a river as the flow edges cool and raise levees. Gradually, the cooling sur­face of the river congeals and a crust develops, especially in downstream parts. Once formed, the crust thick­ens from the underside as cooling lava adheres to it. within a lava tube, and still a searing 1100°C or more, lava can travel large distances—much further than a surface flow of the same volume. When the lava supply to a tube system stops, and if the lava within it is still sufficiently hot, it contin­ues to flow, draining the tubes and leaving empty tunnels. Often the ceiling collapses without the sup­port of liquid lava, leaving channels in the surface lava. Dozens of lava tubes or caves have been found in Auckland, most often during excavations for build­ings or roads. Several lava caves are noted as prehistoric Maori burial sites. One cave at Crater Hill in Mangere even concealed an under­ground press used for printing sub­versive literature during World War II. Auckland's known lava tubes are quite short, because of collapses or lava blockages. The longest and best preserved is the 290m Wiri lava tube that once carried lava from a small scoria cone called Wiri Mountain or Matukutururu. Win lava tube has excellent ex­amples of lava flow patterns and other features that give it high scien­tific and educational importance, but it has been under threat of quar­rying for many years. The owners, New Zealand Railways Corporation, have recently agreed that it should be protected, and negotiations are under way to ensure that it will be. [Chapter-Break] Bejewelled with volcanic  monticules and set between two harbours, the site for Auckland has long been admired for its natural beauty. Best remembered of the city's earliest settlers, Sir John Logan Campbell wrote excitedly that the view from the summit of Mount Hobson (Remuera) surpassed that even from the Acropolis in the or­nate Greek city of Corinth. For hundreds of years before Campbell's time, Maori tribes fought for occupation of the district, rich as it is with fertile volcanic soils for gardening, coastal waters for fishing and hills for pa sites. The city is still known by the Maori name for the isthmus, Tamaki-makau-rau, "Tamaki of the hundred lovers"--a popular place indeed. In Maori mythology, Auckland's isthmus sustained its volcanic wounds in a battle between the mys­tical forest-dwelling Turehu people of the Waitakere and Hunua Ranges. During the conflict, which came to  be known as Pakurangarahihi, a tohunga from the Hunua side caused the sun to rise prematurely, blinding the Waitakere combatants. Many were brutally dispatched in the re­sulting confusion. When night fell once again, the Hunua warriors pressed on towards the Waitakere Ranges, but didn't get far. A Waitakere tohunga invoked the volcano deity Mataoho to intervene, and he promptly threw the whole isthmus into convulsions of vol­canic activity. The Hunua warriors were quickly put to rout by great explosions, tides of lava and billow­ing ash. However, fires started by the volcanoes swept towards the for­ests of the Waitakeres, so a tohunga had to call upon rain to quench them. To this day, Auckland's swarm of volcanic features, together with high rainfall in the Waitakere Ranges, remind us of these events. Not surprising, then, that the Maori who occupied the land much later were keen to keep Mataoho happy. Offerings to placate him were made in the crater of Mount Eden, which has the shape of an enormous food bowl. Regardless of how they came forth, the volcanoes were not the last marks to be made upon Auckland's landscape. The Maori who chose to make the district their home, start­ing perhaps 1000 years ago, were quick to clear the forests and shape the volcanic land to their liking. What we know of these people comes from a melding of archaeo­logical information with oral tradi­tions (like the stories of Mataoho) and tribal lore passed on by kaumatua (elders). Tribal stories recall Titahi, chief of the Ngati Awa, as a famous builder of the impressive pa on Auckland's volcanic cones. The col­lective name for the pa was "Nga Whakairo a Titahi"—the carvings of Titahi. By the seventeenth century, many cones had been sculpted, their natu­ral curves transformed to flights of terraces. All the earthmoving was done by hand, aided only by stone and wooden tools. It possibly took generations to produce the final form of each pa. Terraces were built primarily as house sites, with food storage pits, hearths and open ground nearby. Gradually, as the population of a pa increased, terraces were added to accommodate new families. The fam­ily of the chief lived near the sum­mit of each pa. The defensive role seems to have come later in the development of ter­race systems. The growing popula­tion of Tamaki-makau-rau, and in­creasing attacks by tribes from other districts, led to the construction of palisades and defensive ditches to discourage invaders. Carbon dates suggest that cone pa were in general use in the 15th cen­tury. Population of the district reached a peak about the 16th and 17th centuries, with most of the populace coming from a cluster of tribes known collectively as the Waiohua. In total, Maori of Tamaki-makau‑rau built 33 pa on volcanic cones. They ranged from the massive earthworks of Maungakiekie to a few terraces on Motukorea, which, like most pa, was not occupied con­stantly. It is, apart from Rangitoto, the least modified of all Auckland's volcanoes. Cleared of the original forest, the lava stonefields surrounding the pa were intensively utilised. Radiating like a cobweb from each pa was an array of stone walls, delineating a garden system. Stone was also cleared from the soil and gathered into heaps. Rather than simple clearance structures, the heaps were used to warm soil placed in and around them to gain an ex­tended growing season for crops brought from warmer climates. Kumara, yam, taro and other veg­etables were grown in the fertile vol­canic soils. During fallow periods, the gardens became smothered in bracken. Over the years, segments of the garden array were cultivated in sequence, sometimes taking a gen­eration to complete the cycle. Some of the stonefield garden sites were huge. It has been esti­mated that Maungakiekie had 1000 hectares of garden to support its population. House sites were scat­tered among the gardens, so the walk to work was not too long for the in­habitants. The stonefields were probably settled before the cone pa. The earli­est carbon date obtained for Maori occupation in the volcanic field sug­gests people were living at Wiri Mountain (Matukutururu) from about 905-1405AD. The majority of Auckland's pa were abandoned after a series of con­quests by invading tribes decimated the local people. In the 1700s, Ngati Whatua from the Kaipara drove the Waiohua people from the Tamaki isthmus. In the 1820s, they in turn were routed by musket-toting Ngapuhi raiders from the north, and when European settlers arrived soon after, the isthmus was virtually de­serted. The following decades saw fur­ther massive changes wrought upon the landscape, and these led ulti­mately to the modern city of Auck­land. From the hills of regenerating manuka and bracken, not long va­cated by Maori gardeners, new farms were cleared and ploughed. The set­tlers, too, made good use of basalt rocks cleared from the lava fields for stone walls, some of which still bor­der suburban sections. In the mid-1800s the view from Mount Eden was predominantly ru­ral, but it was not long before the site of the city which had been sur­veyed from that summit in 1840 was thick with houses and roads. The growing city was hungry for construction materials. Basalt scoria was used for early roads, and lava for some of the first permanent buildings. Many of the scoria cones were scarred by quarrying, and a few removed altogether for railway bal­last. Mount Smart (Rarotonga) was quarried from a cone over 50m high down to its roots by the Railways Department. During the last stages of excavation a stadium was thoughtfully constructed out of the rock pile. On Mount Albert—a cone decapitated in the period of railway, and later motorway, construction sports fields were built in the quarry pits. A few of Auckland's historic buildings were built of stone hewn from the basalt lava flows. St Andrew's Presbyterian Church in Symonds Street was the first to be built from that material (taken from flows at Newmarket) in about 1850. The Melanesian Mission at Mis­sion Bay and Kinder House in the suburb of Parnell were constructed of lava taken from the foreshore of Rangitoto Island. Near St Andrews the defensive wall of Albert Barracks was also built from blocks of lava. It was a conspicuous but unsightly fea­ture of early Auckland, and had mostly been demolished by 1871. Part of the structure still stands in the grounds of the University of Auckland. Another use of the lava flows that, through the centuries, has been a focal point for settlement around Auckland is the supply of water. The lava flows are very porous, so rain­water falling on the surface rapidly percolates downwards until it reaches a non-porous layer. In Auck­land, that is the old surface of sedi­mentary rocks that was buried by the lava flows. Imprisoned beneath the lava flows, the pre-volcanic topography of ridges and valleys still exists, and, like rivers on the surface, the groundwater follows the buried val­leys. At the far end of lava flows, where such valleys are close to thesurface, the water can emerge as springs. Upstream, the aquifer can be tapped by sinking a well into it. Western Springs, at the foot of lava flows from Three Kings and the contiguous Mt Eden and Mt Albert flows, was one of Auckland's earli­est municipal water supplies. The springs were dammed and exca­vated to form a reservoir lake. The massive steam-driven pump still on display at the Museum of Transport and Technology pumped water up to a series of reservoirs from 1877 until 1928. At Onehunga, water for munici­pal supply is extracted from four wells sunk into One Tree Hill lava flows. An estimated 27,300 cubic metres of water per day flows through that aquifer, reaching it from as far as five kilometres away through lava flows which fill an an­cestral river valleys beneath the con­temporary terrain. Many of the in­dustries that used to operate in Onehunga, such as wool scourers and tanneries, were attracted there by the opportunity of cheap water from the ground. The municipal water supply in Auckland has benefited from volca­noes in another way. Water from Western Springs and early Onehunga wells was pumped to res­ervoirs constructed on Mount Eden and One Tree Hill respectively. Gravity was then, as now, an inex­pensive method of distributing wa­ter to houses and factories. Most of the cones support one or more reservoirs, forming nodes in the region's bulk water supply net­work. Most go unnoticed, except by the few observers who detect a pe­culiar angularity in the outlines of some of the cones. Others are dis­tinctly obtrusive, like the concrete "crown" topping (and incidentally, saving from quarrying) the last re­maining of the Three Kings. All the cones bear marks from Auckland's growth. Quarries at Wiri extract rock products selectively to make the best use of them. Hard ba­salt from lava flows is used predomi­nantly as base material in road con­struction, but also as road sealing chip, concrete aggregate and railway ballast. The major use of porous scoria is for drainage and soakage purposes. The construction of the airport and Mangere sewage ponds required huge quantities of fill that was ob­tained by flattening several South Auckland cones. The volcanic cones remaining within the city are centrepieces for its parks—havens from the urban fray. The same cannot be said for those in Auckland's hinterland, or for the lava fields which are still re­garded as sources of rock rather than scientific, historic and aesthetic re­sources. Of all the volcanoes, Brown's Island alone escaped quar­rying, but it does carry a reservoir on its shoulder. [Chapter-Break] Over the city  of Auckland there hangs a question, per­haps triggered in people's minds by the way the morning mist clings eerily like smoke to the sum­mit of Rangitoto: Will there be an­other eruption? There is no doubt among geolo­gists that the answer is yes. Given the long record of intermittent erup­tions for the Auckland Volcanic Field, there is no reason to think they won't continue. Since all pre­vious eruptions have come from completely separate magma batches, a future eruption is likely to burst out somewhere between ex­isting centres. Ian Smith, a geologist at the Uni­versity of Auckland, has studied the mineralogy and chemistry of vol­canic deposits to find out about the nature and depth of their source. I asked him what he thought would happen next in the Auckland Vol­canic Field. "I believe the field is hotting up, and I'd predict the next eruption to be Rangitoto-sized." Rangitoto contains 58 per cent of the total volume ever erupted by the Auckland volcanic field, so it is far larger and, Smith says, different from all the other volcanoes. "Subtle changes in its mineralogy suggest that the magma source was shal­lower, and more melting occurred than in previous eruptions. Rangitoto marks a fundamental change in the Auckland field, and future eruptions will probably be bigger and more frequent. But we need the next eruption to find out for sure." Predicting where and when that next volcanic outburst will occur is no easy matter. Seismometers are be­ing set up at key locations around Auckland by Civil Defence and the University of Auckland to monitor movement of the magma. Geologists estimate that Aucklanders would receive, at best, two weeks' warning of an erup­tion—enough time, hopefully, to save the city from becoming a latter-day Pompeii.

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