Search This Blog

Saturday, 20 January 2018

The Royal Botanic Gardens and climate change

We had to get to the Australian Museum a few weeks back, but the night was warm and we had some time to spare, so we took the scenic route.  From the ferry, we strolled around the harbour's edge to the Opera House, and on through into the Royal Botanic Gardens.  It took us a little longer, but we knew in advance that it would be worthwhile.  It always is, and not just because my wife and I both took our first degree in botany.

It is suffering right now, from one of the effects of climate change, but I will come to that in a moment.

Sydney's Gardens were founded in 1816.  They aren't the oldest in the world, for Padua, Paris, Edinburgh, Cambridge, Rio de Janeiro and Munich are all older, but few gardens could have such a fine setting.  Certainly the greatest of them all, Kew, has less to offer in the way of vistas.

It was probably fitting that Australia should establish Botanic Gardens so early, since so much of the history of white exploration and settlement was tied up with botanists and naturalists.  Not only was there Sir Joseph Banks, who sailed with Cook to Botany Bay, but Robert Brown (who told physicists about what we now call ‘Brownian motion’, and who also told biologists about the cell nucleus), Allan Cunningham, and any number of other botanists who spent time in the young colony: you can find traces of some of them in the gardens.  The tradition was later to lead Charles Darwin, T. H. Huxley to our shores, and the naturalists are still coming, even today.

At first, the gardens were seen as little more than a glorified and official vegetable garden, but slowly the plant collection developed.  The name of the water near the gardens is a reminder of this earlier role, as it is still called Farm Cove.  Six months after the first settlement, there were ‘nine acres in corn’ at the first farm, but the soil was poor, and the crop was a failure, so agriculture moved elsewhere, and the area became a centre for acclimatising new plants from overseas.

If you visit the Gardens and find a poor and unkempt looking garden bed, you are looking at a reconstruction of this first ‘farm’, but that was soon displaced by other activities.  People who wanted to grow oaks to remind them of ‘home’ could obtain acorns there, and those with damp patches on their farms could get bamboo plants.  By 1816, it had become more of a plant collection, and by 1825, there were more than 3000 plant species in the collection.  Many of our worst modern plant pests came into the country this way.

Even so, Allan Cunningham, whose tomb is to be found in the gardens, still referred to it slightingly in 1838 as the ‘Government cabbage-garden’.  The science of botany had come to take second place to horticulture, with convicts being trained in practical farming there.  The gardens declined until 1848, when Charles Moore, a trained botanist, started a 48-year reign as Director of the Gardens, and from then on, they were to be truly Botanic Gardens, as well as being the home of the National Herbarium.  This is a research collection of dried plant specimens, used in the identification of unknown species.

Moore's successor, Joseph Maiden, was also a botanist, and it showed: one of Maiden's daughters was actually named Acacia!  This is the scientific name of what we plebs call a ‘wattle’, and I have this theory about the family sitting around, asking each other, ‘What'll we call her, what'll we call her?’  Well, it's only a working theory . . .

Botanic or Botanical Gardens?  Most Sydneysiders call them the ‘Botanical Gardens’, so I asked a friend who works there, and I was told that ‘botanic’ is the old-fashioned adjective which is part of their official name.  The gardens are indeed ‘Botanical Gardens’, but not in formal matters, it seems.  Still, Sydney people aren't all that formal at the best of times.  Even so, to most people there is only the one ‘Botanical Gardens’, and that is the one at Farm Cove, just to the east of the city.  As you will read in the next paragraph, we actually have three official ‘Botanical Gardens’.  I will say more about the other two branches of ‘The Gardens’ some other time.

Entry to the gardens is free to all.  There may be an entry fee for one or two spectacular temporary displays, but it is well worth paying to see the contents of these.  On the other hand, if you are in a hurry or on a tight budget, there is a great deal more to be seen for free, out of doors, including more than a hundred bird species: you can hope to see at least twenty on any given day.

Sadly, you will also see evidence of climate change there, and two days ago, I went there to record a tidal incursion. The highest "king tide" of the year comes when the planet is closest to the Sun, which happens on January 2. On January 3 this year, there was a high tide in Sydney of 2.07 metres, and the following day, when I was there, it was 2.05 metres.

Along Farm Cove, there is a sandstone wall to stop waves breaking in, and at the bottom, there are drain holes to let rain water out, but if the tide is high enough, the sea comes in. The wall is 86 cm: remember that number.

Here is what I found:







Now just to show how bad it might have been, here is some wave action at the western end, near the Sydney Opera House (or for Sydneysiders, near Man o' War Steps).
The wall is much higher there, but it was easily overtopped. Given the right wind, this would have happened all along. Now here is what I photographed the day before, when the tide was 2.07 metres: this was at North Harbour Reserve, where I have played for 70 years, and I have asked old people, when I was young, about its history.

In the 1930s, the local civic fathers saw fit to "reclaim" a former bay to make North Harbour Reserve. They built a seawall, higher than the highest tide, and pumped in mud to make a level playing field. Some years ago, as the sea started running in, they raised the sea wall and topped it with a path. Well, that defence is failing.

Our local champion of scientific idiocy, Tony Abbott, trumpeted overseas that he had looked at local historical photos of the area, and could find no evidence of climate change.

I have lived and played around North Harbour for 70 years, and I rather think this counts as evidence. That's a king tide that could easily have been 15 cm higher, if there had been a sou'easter blowing: the old men told me all about that happening, and floating one boatshed away. We got off lucky, this time, because the weather was mild.

In 1957, when I was a teenager, a super-high tide at our standard spot for the harbour (Fort Denison) was 6 feet 1 inch, or 185 cm: now, 60 years on, it is 22 cm higher. Two days ago, the CSIRO published estimates that by the end of this century, within the likely lifetime of my grandchildren, tides will be between 45 cm and 88 cm higher than now.

Those tides will be unstoppable, all around the world, and if the upper level is reached, that increase will overtop the stone wall by 2 cm.

One wonders if our do-nothing, look-at-me polly will seek funding to raise both the seawall and the park surface, or if he will just scream "fake news!".

Please share this link: we might manage to get Nero to stop fiddling ...

Sunday, 31 December 2017

New Year in Sydney

First, here are some samples of a Sydney New Year's Eve, taken from expensive seats on Pinchgut, two years back. This year, we and our standard NYE friends will dine at a quiet restaurant away from the lowing herd, then walk back to our house to see the New Year in, on a north-facing balcony, looking away from the glows in the sky. After almost 50 years of harbour fireworks (the first we saw were in 1970), we don't like the discomfort and the heaving crowds.

Beforehand

Things happened to amuse the waiting crowds. Remember the bridge, because it plays a role.

The sun set, but it wasn't 9 pm yet.
Finally, the show began. Look for the bridge and the Opera House.

Look for the bridge and the Opera House. These are our tribal icons.






Among the guests on Pinchgut were two Scots couples who come out each year for the fireworks on the harbour. I fear they may have had to find a new vantage point this year, as the restaurant on the island seems to have disappeared.  Our Australian celebration of New Year's Day owes a lot to our Scots heritage.  Perhaps I am a biased observer.  As my surname implies, my ancestors were Scots.  My family has been here since early colonial days, but we still keep many of the old traditions intact.

Even in my generation, there has always been at least one piper in the family to welcome in the New Year with a skirl, and the bagpipe remains my favourite solo instrument, for I spent my earliest New Year's Eves, standing directly beneath my father's chanter (that's the lowest pipe, the one you twiddle on), taking in the sound and the smell of the pipes.

Perhaps I will learn to play the pipes when I retire.  I will be in good company if I do, for I know of just the pipe band for me, made up entirely of old and retired ‘Scots’, most with broad Australian accents.  Some traditions die hard, even under an Antipodean sun.

Others may celebrate their New Year's Day by nothing more than a day at the beach, or around a suburban backyard pool.  Still, some hardy traditional types will spend the day at a Highland Gathering, engaging in all sorts of strange activities like tossing the caber and wild dancing to pipes that serve to remind them of the hangover they still bear from the night before.

Traditionally, anybody can be a Scot on that day.  My father knew a champion piper called Colin Campbell who was, as it happens, one of the original Australians.  In those days, whites would stress further that Colin was a ‘full-blooded aboriginal’.  Be that as it may, he would appear each year in the New Year's Day piping competitions to play his own spirited rendition of ‘A man's a man for a'that’, and often to take prizes for his playing.  Those who know their Burns, of course, will see Colin's point . . .

But Sydney has always had its unusual Scots.  A hundred years ago, a Chinese merchant of Sydney, one Quong Tart by name, was popularly known to one and all as ‘Quong Tartan’.  He came to the Australian goldfields as a small boy, and was taught English by Scots people, so his accent was well suited to his nickname.  Historical accounts mention that he was an accomplished reciter of the poems of Robbie Burns, including, I imagine, ‘A man's a man for a'that’.

One of the things which strikes tourists about Sydney is the huge range of faces on the street, but this is by no means new.  Now, we call it ‘multiculturalism’, but it used to happen a hundred years ago as well.  Here is what ‘James O'Connell’ wrote in 1836, preserving his spelling:

In George street, the grand thoroughfare, the visiter is amused with the motley group of divers nations, kindreds, and tongues that he encounters.  New Holland is less exclusively the residence of convicts than the reader may have imagined.  Settlers and visiters from all portions of the globe — Spaniards, Frenchmen, Englishmen, Americans, Chinese, Malays, Kanakas or South Sea Islanders, the latter arriving in whale ships, add variety to a scene which, without them, would be varied enough.

‘O'Connell’ was an escaped convict who had clearly spent several New Year's days here before he escaped to Ponape (Pohnpei) in what was then the Caroline Islands, and later to the United States, but let us stay with the present, for now.

Other Australians will spend New Year's Day in the bush.  No, not in A bush, but in the bush.  That is, in what other lands might call a wilderness, a forest, a jungle, or even a heath.  To us, these are all one and the same: they are all ‘bush’.  Where other nations go hiking or back-packing, we go bush-walking.  Last century, we never had highwaymen, but we always had our bushrangers.  We took the word "bushranger" from the Americans, who used it to mean anybody who roamed freely through the forests, but it soon took on the meaning of an armed robber.

‘Bush’ can also mean anything rural, not of the city, as in ‘the city or the bush’, or as in a classic ribald poem, ‘The Bastard from the Bush’, but mainly it refers to those patches of native Australian vegetation which are to be found, even in the middle of a city of nearly four million people like Sydney.

New Year's Day will be a hot and listless high summer day, so the sensible thing to do is to find a shady spot beside a creek, to swim a bit, to eat a bit, to drink a bit, to relax and enjoy the quietness.  One of the joys of Sydney is that you can find clean cool water in a quiet gully, within an hour of the very centre of the city.  The most preferred housing sites have a harbour view, closely followed by those looking over, and surrounded by, bush.

Of course, this can also a drawback, for those patches of bush can flare up into cruel bushfires, but that is something most people prefer not to think about on New Year's Day.  It is high summer, there is cricket on TV, beer in the fridge, and tomorrow will be a time to relax, at least for now.

I might just spend a few days in the bush. After all, ours is an evolving culture.

Still, bliadhna mhath ur.

Saturday, 30 December 2017

Frogging

This went out originally as an ABC Radio National broadcast on Ockham's Razor. It has been edited to disguise locations.

It is a warm and moonless Saturday night.  It is raining, the cloud is down so low on the headland that it qualifies legally and scientifically as mist, and I am wandering around in the dark through dense heathland, half a kilometre from home, with the rain soaking through my broad-brimmed hat, and running down my neck.  Every so often, I stop and shout ‘FROG!’ as loudly as I can.  Then I raise my dripping hat to hear if anything answers.

It is probably fair to ask whether these are the actions of a sane man.  I say they are, but then I know what I am doing.  Or that is my story, at any rate, and I would like to stress here my non-membership of that strange breed, the compulsive froggers, people who sometimes care more for frogs and toads than they do for humans.

I know that I retain my sense of proportion, my sanity, for out there, alone in the dark, I am still rational enough to ask myself what I am doing there.

I am on a headland near Sydney Harbour, in a large patch of bush where there are three, or possibly four species of frog.  After steady rain, there will be equally steady seepage out of the sandy soil for some weeks, and the frogs have a chance to rebuild their numbers.  They gather near the trickling water, they call, and they mate.  Their tadpoles will hatch a few days later and rush through a hurried childhood into premature adolescence, before they join their parents on the drying land.

As a child, I collected tadpoles once or twice in a glass jar and brought them home, but I never succeeded in growing any up to be frogs.  As a young adult, I maintained a genial interest in frogs.  I learned to feed the tadpoles on lettuce, to get them to the adult stage.  Most importantly, I learned to provide them with a rock to rest on, a way out of the water.  Emergent frogs have lungs, not gills, and they will drown if they cannot scramble out.

Many years ago, as a young biology teacher, I acquired by devious means a lockable glass-fronted cupboard, designed for chemical storage.  I bolted it to a corridor wall where passing students could look in.  I bought a narrow glass tank and went through a number of frog-breeding cycles over several years, but I was still not a compulsive frogger.  I just thought it was good for students to have a small ‘zoo’ to look at.  Tadpoles and frogs were a major part of what happened there, along with assorted invertebrates and static demonstrations, but I was definitely not a compulsive frogger.

Later, I moved house, and we soon found that frogs had joined us in our garden.  We got up one rainy morning to find that we had a frothy mass of frog eggs in plastic bowl that lay abandoned in the garden.  Delighted, I dug a small pond, and transferred the eggs across.  Soon after, when I had to build some new stairs and a landing into the backyard, I constructed a much larger pond in the wasted space underneath the stairs.  Friends thought this a little eccentric, but I knew I was still not a compulsive frogger.  Even the friends could see that, when I explained it to them.

Some years later still, I found myself working in a museum, and I was cajoled into working on a project called Frog Watch, that involved both frogs and computers.  I was involved more as a writer and computer person, though I found myself getting more involved in froggy things.  But still I resisted the temptation to become a compulsive frogger.

I met quite a few compulsive froggers while I was there.  One of them noticed a small population of tadpoles sharing a pool with some mosquito fish.  This surprised him, for mosquito fishes will attack most tadpoles, and eat them, working up from the tail.  Most people would have passed on to other things, but this frogger thought about it, and concluded that the tadpole must taste rather awful.  A true man of science, he tried eating several of the raw tadpoles.  They tasted vile, a discovery which may have waited forever, but for the dedicated commitment of this compulsive frogger.

I met a fellow worker, who kept several pet frogs in a tank in his office, where they responded every time his phone rang.  Later, I edited a frog book for another colleague, who kept a one-eyed tree frog in his workshop (it lost the other eye when a truck ran over it, but my colleague nursed it back to health).  I knew I was still not a compulsive frogger, not by any of the rational standards that I could construct.

Pseudophryne australis, otherwise the Sydney red-crowned toadlet.
CC BY-SA 3.0, 
https://commons.wikimedia.org/w/index.php?curid=1185340
Then I moved house again.  Soon I started to notice the several frogs living around my house.  I bought tapes to identify them (you ‘earball’ frogs rather than eyeballing them), and I started to learn how to provoke certain species to call.  Then one day I found a small frog in my front yard, did a quick double-take.

With delight, I realised that the seepage drain near my front gate was home to a member of an endangered species, a Sydney Red-crowned Toadlet.  I was still not a compulsive frogger, but now I was distinctly interested.

Since then, I have been trying to map the frog's distribution in the local area by going out in wet weather and listening for the toadlet's distinctive call.  Somebody in Canberra told me once that the Corroboree Frog, another member of the same genus, will answer if a male human voice bellows ‘FROG!’ nearby.  Testing that theory is what leads me out into the wilderness on damp still nights, shouting in the dark.  That and finding out just how healthy the local population is, but I am still not a compulsive frogger.

My little toadlet lives in some two hundred pockets of land around Sydney.  In all likelihood, each population carries different genes, but there is no flow of genes between the different localities.  Each group is an isolated remnant.  If any group dies, it will not be replaced by new colonists moving in, for they cannot swim over the salt water of the harbour.  There is no bridge for them to use, and pioneers cannot hop over the 5 kilometres of settled ground to get here from the next pocket.
The toadlet's distinctive  underbelly.
By Tnarg 12345 at the English language Wikipedia, CC BY-SA
3.0, https://commons.wikimedia.org/w/index.php?curid=2652554

If any isolated group dies out, its small part of the genetic diversity dies with it.  The special genes that they alone may have are no longer available to the population as a whole.

It is a simple enough principle: even the ancient Romans understood it, when they coined the phrase ‘Divide et impera’ — divide and rule.  It is a cold implacable logical law, and its operation may one day wipe out all of the toadlets.

But why should we worry about one little frog, when there are hundreds of other species in Australia?  Many years ago, Paul Ehrlich taught us that we should think of an ecosystem as rather like an aeroplane which can lose a few bits and still fly.

I prefer to see an ecosystem as a steel bridge.  You can take one rivet away from a bridge, and nothing will happen.  You can remove another rivet, and the bridge will be as steady as ever.  You may even take some more, and still do no harm.  But somewhere along the way, you will take out one rivet too many, and the bridge will come tumbling down.  Ecosystems are robust, they can manage without some of the key species, but sooner or later, they start falling apart.

Biodiversity in a species works the same way.  Eliminate a few unusual genes, and no harm will arise, not yet.  Take a few more rare genes away, and there will still be no problem.  Sooner or later, though, some other change will mean that one of those eliminated genes will be needed.  By then, it won't be there, because the gene's minders have died, and the gene has died with them.  All over Australia, the frogs and toads are reminding us, calling ‘rivet, rivet’, but nobody cares, for the frogs' bridge is still standing.  It sags a bit, it may sway perilously from time to time, but it is still there.

It is a warm and moonless Saturday night.  It is raining, the cloud is down so low on the headland that it qualifies legally and scientifically as mist, and I am wandering around in the dark through dense heathland, half a kilometre from home, with the rain soaking through my broad-brimmed hat, and running down my neck.  Every so often, I stop and shout ‘FROG!’ as loudly as I can.  Then I raise my dripping hat to hear if anything answers.

I know now why I am there in the dripping mist.  I am still not a compulsive frogger, but I think I understand them now.

Monday, 18 December 2017

Food preservation

Here's a small sample from Not Your Usual Science, which is now finished, but getting a last polish. That will take a while, as it ended up at 460,000 words. It will be out on Kindle in a month or two.
The illustrations are from a recent visit to Sri Lanka, where I saw fish being sun-dried.

Negombo beach, tuna.
Nobody ever sat down and thought “today, I will invent technology and change society”. It was more likely to be a matter of certain aspects of technology emerging, after which people used the new ideas, and only realised later that they had changed their society. Even more likely, they found a new way, used it, and changed their habits, which in turn changed society.


Before the development of agriculture, people had to live a nomadic life, moving after the food, following the seasons. Once they had ways of growing food near a permanent home, they could settle in one place, but then they needed ways to preserve and/or store food, to stop it going bad.
A closer view of the tuna

The process would have begun slowly, because even nomads knew how to smoke meat over a slow fire, or use sunlight to make beef jerky. Fish could also be dried or smoked. Before people knew about germs, salting was a good way to stop germs growing on meat.

Water can flow out of living cells and it can also flow back in through the cell membranes. High salt concentrations outside a cell stop water going back in, so any microbes in salted food soon dry up and die. When beef or other meat is dried, the salts in the meat are left behind, and once again, the salt levels stop bacteria and fungi from growing. (If you want to know what is going on here, the key word is osmosis, but right now, we are discussing history.)

Bees have used the drying method for millions of years, collecting nectar and fanning it to evaporate off most of the water, changing the nectar to honey. Spores and germs that fall into the honey simply cannot grow. When sugar cane is crushed, the juice is boiled and this concentrates the solution to stop any fungi or bacteria surviving in it.
All sorts of fish are dried.


By good luck, heating the cane juice also destroys a natural enzyme in the sugar cane which breaks the sucrose molecule down into simpler sugar molecules which are less useful, and the whole sugar industry depends on destroying this enzyme.

Islamic societies around the Mediterranean followed to a greater or lesser extent the teaching in the Quran that drinking alcohol was wrong, but even pious Muslims still liked cooling drinks. Highly concentrated fruit juice and sugar would keep forever, as nothing could live in it, but this cordial could be mixed with cool water to make a pleasant drink.

They are mainly carried inland and sold. Without fish, the
inland folk would have an iodine deficiency and goitre.
In a very real sense, the population depends on dried fish.
When the Egyptians preserved dead bodies, they used a similar method, but they replaced ordinary salt with natron, a mixture of sodium carbonate and bicarbonate which, as we have seen, was also used in glass making. The mummies would have tasted better with salt, but as nobody planned to eat them, natron was fine.

All the same, it would be reasonable to suspect that the Egyptians knew about salting meat before they made mummies, which would mean they must have started salting meat at least 4500 years ago.
Whatever method is used, preservation either sets out to kill the food-spoiling microbes, or to slow them down, making the food last longer. Warming up food makes a perfect environment for germs to multiply, and “food poisoning” often begins with warmed-up food being set aside and then heated again.

Geoffrey Chaucer was an English poet and scholar who died in 1400, as the Middle Ages came to an end, but he knew all about this danger. In his Canterbury Tales, Chaucer has a character accuse a cook of ignoring this risk. The Jack of Dover mentioned here was almost certainly a pie of some sort:
And many a Jakke of Dovere hastow soold,
That hath been twies hoot and twies coold.
 In more modern (but similar) language, this says:
And many a Jack of Dover hast thou sold,
That had been twice hot and twice cold.
Refrigeration is a good way of slowing down germs, but as Chaucer knew, more than 600 years ago, the cook’s habit of re-warming food made it potentially deadly. Unlike Chaucer, we realise that repeated warming of food can increase the number of bacteria to dangerous levels, but even without knowing about germs, Chaucer knew that reheated food was dangerous.

We can look at a food preservation method today and see the science which lies behind it, but each of the methods must have been originally discovered by chance, perhaps when an animal drowned in a brine pond, and was later found, free of rot.

Food left too long over a low fire may have been dried or smoked, wheat and barley stored in pots in hot dry places stayed dry and undamaged, and so on. Freezing of dead animals caught in a snowdrift may have preserved their meat, but looking into this actually killed one scientist, Francis Bacon, also known as Lord Verulam:
Mr Hobbs told me that the cause of his Lordship’s death was trying an Experiment … it came into my Lord’s thoughts, why flesh might not be preserved in snow, as in Salt. They … bought a Hen, and made the woman exenterate it, and then stuffed the body with Snow, and my Lord did help doe it himselfe. The snow so chilled him that he fell immediately ill … they put him into a good bed, warmed with a Panne, but it was a damp bed that had not been layn-in in about a yeare before, which gave him such a colde that in 2 or 3 dayes … he dyed of Suffocation.
— John Aubrey, discussing Francis Bacon (1561 – 1626), Aubrey’s Brief Lives, 179.
Whichever way the food was preserved, even without knowing anything about the spores, bacteria or fungi, humans stopped their food spoiling. The result was that people were able to live through bad seasons or times when there was no food to be had. They were also able to store food such as turnips or hay to keep animals alive, and dried foods were light enough to carry on long journeys.

Unfortunately, some preservation methods also destroyed any vitamins that might have been in the foods. Sailors and other travellers who tried to live on salt meat and ship’s biscuit (a very dry sort of bread) risked developing ‘disease’, as scurvy used to be called. On short voyages, the passengers and crew had enough vitamin reserves in their bodies to stay fairly healthy, but as voyages grew longer, people began to sicken, or even die, killed by the preserved food they thought was keeping them alive.

Pickling with a mixture of salt and vinegar can stop vegetables spoiling. Salt does not destroy vitamin C, the cure for scurvy. Salt meat has no vitamin C because the original meat had none, but pickled cabbage, sauerkraut, still has most of the vitamin C found in the original cabbage. Lime juice was boiled to a concentrated germ-resistant syrup. That usually kept some of its vitamin C, so long as the lime juice had not been boiled in copper pots. Copper surfaces are very good at destroying the vitamin.

Preserved foods allowed Europeans to discover the whole world and then dominate it. It was a mixed blessing, when you consider how they treated those they dominated!

Thursday, 14 December 2017

Bushfire backgrounder

Bushfires are a part of high summer in Australia. In winter each year, Australians carry out control burns, small fires aimed at reducing the amount of standing fuel. These may help to contain the fires or stop them, but given the wrong weather, no amount of control burning can stop fires happening somewhere. The science is against any other outcome.

A note first about terms: in Australian English, ‘bush’ is what others might call forest, heath or scrub. The term was brought to Australia by early settlers who had previously lived and worked in North America, so this quintessentially Australian term is in fact an early American import! A ‘bushfire’ is a fire running wild in the bush. 

Many botanists in the past have been forced to change their research to ‘bushfire regeneration’ after their plots were burned out, and the cost of fires has meant that there has been a great deal of research on the topic.

First, let us consider the biology of bushfire in Australia. Fire is a natural part of the bush cycle, so the natural environment should survive fairly well, just so long as there is no heavy rain, too soon afterwards. That is why the fire fighters will concentrate on saving property and lives.

They will fight fire with fire, knowing that what they burn deliberately will grow back again, refreshed by the flames. Australia’s bush, after all, lived with fire for many millions of years, long before humans came here. The bush will grow back after the fires have done their worst.

Next, let us consider the geology and geography of urban Sydney bushfires. When the first Europeans reached Australia in 1788, they settled in what is now Sydney, either on flat land near the sea or on the ridges.

Sydney sits on a bed of sandstone, two to three hundred metres thick, with joints running north-south and east-west. It was laid down in a Triassic delta, rather like Bangladesh today, with a huge river braiding back and forth, washing out the finest minerals, the clay and other mineral-rich sediments, and leaving just the quartz grains behind. The grains were rounded, and had probably been in an earlier sandstone somewhere else, but they settled where Sydney is now, almost 200 million years ago, waiting to play their part in shaping modern Sydney.

Some of the sandstone beds are better bonded than the others within this ‘Hawkesbury sandstone’, but they are otherwise pretty much the same, right through the deposit. (Hawkesbury, in case you are wondering, was a minor 18th century English politician who had a local river named after him. The stone was later named after the river.)

In the last Ice Age, the sea level around Australia was much lower, due to all the water tied up in the northern glaciers. Then, today’s Sydney Harbour was a river valley, shaped by the jointing pattern in the sandstone. Joints, planes of weakness in the stone, were eroded into crevices which became valleys, with the more resistant sandstone forming ridges. Later, the sea level rose, creating a ‘drowned river valley’ with a characteristic fern leaf shape, the modern Sydney Harbour. A few of the higher ridges have a shale capping which offered rather better soil than the sand which derives from sandstone.

The first whites settled on the coast, then headed (a) for the flat land of the ridges, where roads were easier to build, and (b) for the richer soil on the shale-capped ridges. First, they built small farms and market gardens, then roads were built to service these, and soon the residences followed, as a young city grew. Down in the valleys, close to the sea, the bush was left alone. It was too hard to build roads down to there, and so people left it alone. Even today, much of the valley bush is preserved, with homes sitting on the ridges above: a sure recipe for trouble, because heat and flames rise.

Fuel builds up in the bush over a period of years. Gum trees shed their bark, branches and leaves, smaller shrubs in the under-storey die and are replaced by others, and after a few years of recovery, the lowest three metres or so is a closely packed mass of dead and drying twigs. Until they break and fall, these pieces of finely divided wood rot very little in the dry bush, and even on the forest floor, rotting is a slow business, for the sandy soil drains fast after rain. Heath regenerates fast.

Some of them can be ready to burn again, just six months after a major fire. Other areas can take ten to twenty years to be ready for a major burn. As a general rule, after 40 or 50 years, any area at all will be ready to sustain a ‘blow-up fire’.

Now for the physics of bushfires in Australia. When any fire starts, it begins very slowly. It takes time to develop from a maker of smoky wisps into a maker of misery. The dangerous fire is one that roars and gusts through the tree tops, the crowns of the trees, a firestorm traveling at 50 kilometres an hour or more, leaping ahead of itself, and destroying all in its path.

Crowning fires can cross 400 metres of open water, as the sparks and burning rubbish fly up in the roaring flames, and then tumble down on the other side. Any footage you see on your local TV will be of these crowning wildfires.

You will see flames gouting 30 metres or more into the air, searing the upper branches of gum trees, leaping across the fire breaks, and almost impossible to control until the weather improves.

Now let us look at the question of weather and bushfires. The weather is the last factor in the bushfire equation. At the moment, we have hot dry nor-westers, gusting at up to 50 knots, pushing the fires downhill as well as up. Usually, a fire front can be beaten as it crests a ridge.

Fires go fast uphill and slow downhill, but they do run downhill. On the forward side of any advancing fire, you will find a wind blowing towards the flames at the front of the fire. If you can set small fires on the far side of a ridge, they will gather strength and rush up, sucked in by the fire wind from the blaze on the other side, until the small fires meet the major fire coming the other way.

In this style of fire-fighting, the major fire limps over the ridge, only to find that most of the fuel in its path has already been burned. Starved, it falters like a wounded beast, and puny men and women rush in to attack it with sprays and hoses. But with high winds, this ploy is too dangerous to attempt, as the fire lighters in its path could easily be over-run, as it leaps over the fire break they have just made.

Within hours of the fire, the seeds will be dropping from the woody fruits of the she-oaks, Hakeas and Banksias, and the trunks and underground stems of other plants will already be starting to shoot. In three weeks, there will be green all over the bush. In time, the bush will recover, and so will the animals. The homes can be rebuilt, and lives, so long as they have not been lost, will go on. It is all part of the natural cycle. The animals will take longer, but some will survive, and others will move in from unburnt areas, but recovery is a slow natural cycle.

Thursday, 30 November 2017

Australian Backyard Earth Scientist

I have just published my peculiar novel, Sheep May Safely Craze on Kindle. This is a comic romp through history, literature, higher mathematics, lower mathematics, logic, mythology, cosmology and the dark side of pea soup, and it is available on Kindle. You can read more about it here. 

Anyhow, I have now turned back to earth science for younger readers again, as the editor's responses come my way from the Number One editor at the National Library of Australia, Jo Karmel. This is the fifth book we have worked on together (or seventh, if you count new editions separately), and there's another on the way

Anyhow, by the time we are finished, Australian Backyard Earth Scientist is going to be a good book, but here are some left-overs, more suited to older readers. These might have been epigraphs, but we don't do those for younger readers. Here are the unused quotes, and a few pics from my short-list (~250 shots at last count).

Earth science

Folds, Mt Pilatus, Switzerland.
A rolling stone gathers no moss.
— Proverb, dating back to the 16th century.

To a naturalist nothing is indifferent; the humble moss that creeps upon the stone is equally interesting as the lofty pine which so beautifully adorns the valley or the mountain: but to a naturalist who is reading in the face of the rocks the annals of a former world, the mossy covering which obstructs his view, and renders indistinguishable the different species of stone, is no less than a serious subject of regret.
― James Hutton, Theory of the Earth, vol. 3, 46.

A rock or stone is not a subject that, of itself, may interest a philosopher to study; but, when he comes to see the necessity of those hard bodies, in the constitution of this earth, or for the permanency of the land on which we dwell, and when he finds that there are means wisely provided for the renovation of this necessary decaying part, as well as that of every other, he then, with pleasure, contemplates this manifestation of design, and thus connects the mineral system of this earth with that by which the heavenly bodies are made to move perpetually in their orbits.
— James Hutton. Theory of the Earth, with Proofs and l1lustrations, Vol. 1 (1795), 276.

An historian should, if possible, be at once profoundly acquainted with ethics, politics, jurisprudence, the military art, theology; in a word, with all branches of knowledge … It would be no less desirable that a geologist should be well versed in chemistry, natural philosophy, mineralogy, zoology, comparative anatomy, botany; in short, in every science relating to organic and inorganic nature.
— Sir Charles Lyell, Principles of Geology, Vol. 1, 3, 1835.

…the successive series of stratified formations are piled on one another, almost like courses of masonry.
— William Buckland, Geology and Mineralogy, Considered with Reference to Natural Theology, Bridgewater Treatise 6, Vol. 1, 37, 1836.

Folds and faults, S. coast NSW.
[When] spring and summer come round, how easily may the hammer be buckled round the waist, and the student emerge from the dust of town into the joyous air of the country, for a few delightful hours among the rocks.
— Sir Archibald Geikie, in The Story of a Boulder: or, Gleanings from the Note-book of a Field Geologist (1858), viii.


Apart from its healthful mental training as a branch of ordinary education, geology as an open-air pursuit affords an admirable training in habits of observation, furnishes a delightful relief from the cares and routine of everyday life, takes us into the open fields and the free fresh face of nature, leads us into all manner of sequestered nooks, whither hardly any other occupation or interest would be likely to send us, sets before us problems of the highest interest regarding the history of the ground beneath our feet, and thus gives a new charm to scenery which may be already replete with attractions.
— Sir Archibald Geikie, Outlines of Field-Geology (1900), 251-2.

Experimental geology has this in common with all other branches of our science, petrology and palaeontology included, that in the long run it withers indoors.
— Phillip H. Kuenen’ 'Experiments in Geology', Transactions of the Geological Society of Glasgow (1958), 23, 25.

No Geology without Marine Geology!
— Phillip H. Kuenen, Title of paper, Geologische Rundschau, 47(1), 1958, 1 – 10.

Geology itself is only chemistry with the element of time added.
— Ralph Waldo Emerson, Aspects of Culture, The American and Continental Monthly, Volume 1, April 1870, 5.

Beneath all the wealth of detail in a geological map lies an elegant, orderly simplicity.
— Tuzo Wilson, As quoted G.D. Garland in obituary 'John Tuzo Wilson', Biographical Memoirs of Fellows of the Royal Society (Nov 1995), 552.

Atoms

Hexagonal packing can turn up unexpectedly.
To understand the very large, we must understand the very small.
— Democritus (470 – 380 BC)

… in the field some amount of information concerning igneous rocks can be obtained by rubbing down the chip on a grindstone and using a whetstone, carborundum file, or water of Ayr stone for the final grinding. By these and other methods … there are obtained slices of rocks which, though thick, uneven, scratched, and all that is bad, from the point of view of the professional maker of thin sections, are nevertheless capable of yielding much information. With a pocket lens it is possible to make out from such a 'thin' section the nature of the minerals present, the texture and the nature of the rock.
— Frank Rutley, Elements of Mineralogy, 22nd edition, 1915, p. 104.


The difference between a piece of stone and an atom is that an atom is highly organised, whereas the stone is not. The atom is a pattern, and the molecule is a pattern, and the crystal is a pattern; but the stone, although it is made up of these patterns, is just a mere confusion. It's only when life appears that you begin to get organisation on a larger scale. Life takes the atoms and molecules and crystals; but, instead of making a mess of them like the stone, it combines them into new and more elaborate patterns of its own.
— Aldous Huxley (1894 – 1963), Time Must Have a Stop. London: Chatto and Windus, 1945, chapter 14.

A crystal lacks rhythm from excess of pattern, while a fog is unrhythmic in that it exhibits a patternless confusion of detail.
— A. N. Whitehead (1861 – 1947), An Introduction to Mathematics. Oxford: OUP, 1948.

 Change

One generation passeth away and another generation cometh: but the earth abideth forever.
Holy Bible, Ecclesiastes, 1:4

To explain the observed phenomena, we may dispense with sudden, violent and general catastrophes, and regard the ancient and present fluctuations . . . as belonging to one continuous and uniform series of events.
— Sir Charles Lyell (1797 – 1875), Principles of Geology.

Rather more than a century ago Sir Charles Lyell, then an Oxford student, noticed that a small lake on his father's Scotch estate was capable of depositing an appreciable layer of limestone on its bottom within quite a few years — and on his discovery that rocks could be built up as well as worn away is based a large part of modern geology.
— A. W. Haslett, Unsolved Problems of Science, London 1937.

Thermal mud, Orakei Korako, New Zealand
Compared with what we think of as long periods in our everyday calculations, there must have been enormous time and considerable variations in circumstances for nature to lead the organisation of animals to the degree of complexity and development that we see today.
— Chevalier de Lamarck (1744 – 1829), Philosophie Zoologique.

We may confidently come to the conclusion, that the forces which slowly and by little starts uplift continents, and that those which at successive periods pour forth volcanic matter from open orifices, are identical.
— Charles Darwin, Journal of Researches into the Natural History and Geology of the Countries Visited During the Voyage of H.M.S. Beagle Round the World, 2nd edn. (1845), ch. XIV, 311.

… millions of our race are now supported by lands situated where deep seas once prevailed in earlier ages. In many districts not yet occupied by man, land animals and forests now abound where the anchor once sank into the oozy bottom.
— Sir Charles Lyell, Principles of Geology, Vol. 1, 373, 1835.

While a glacier is moving, it rubs and wears down the bottom on which it moves, scrapes its surface (now smooth), triturates the broken-off material that is found between the ice and the rock, pulverizes or reduces it to a clayey paste, rounds angular blocks that resist its pressure, and polishes those having a larger surface. At the surface of the glacier, other processes occur. Fragments of rocks that are broken-off from the neighbouring walls and fall on the ice, remain there or can be transported to the sides; they advance in this way on the top of the glacier, without moving or rubbing against each other … and arrive at the extremity of the glacier with their angles, sharp edges, and their uneven surfaces intact.
— Louis Agassiz, La théorie des glaciers et ses progrès les plus récents. Bibl. universelle de Genève, (3), Vol. 41, p.127. Trans. Karin Verrecchia.

On the morning of May 8th, 1902, the clocks of St. Pierre ticked on towards ten minutes of 8 when they would stop forever. Against a background of bright sunshine, a huge column of vapour rose from the cone of Mont Pelée.
A salvo of reports as from heavy artillery. Then, choked by lava boiled to white heat by fires in the depths of the earth, Pelée with a terrific explosion blew its head off.
— Fairfax Downey, 'Last Days of St. Pierre', in Disaster Fighters, G. P. Putnam's Sons.

Temperature gradients in ordinary [volcanically] quiet areas range from less than 10 to as much as 50 degrees Celsius per kilometre.
— A. E. Benfield, 'The Earth's Heat', Scientific American Reader (1953), page 71.
Volcanic bombs in the making, Mt Yasur, Tanna, Vanuatu.

Naturally a good deal of thought has been given to how the immense energy of volcanoes might be harnessed for man's use. It has been done on a relatively minor scale in several countries, notably Italy and Iceland.
— A. E. Benfield, 'The Earth's Heat', Scientific American Reader (1953), page 86.

Just as the level of Stone Age finds gives an average sinkage of 9 inches in a hundred years, so calculations based on Roman remains suggest a similar figure… Presumably it is still doing so to-day, although it will be another five hundred or a thousand years before the problem of maintaining the Thames embankment will begin to become acute.
— A. W. Haslett, Unsolved Problems of Science, London 1937. (The Thames Barrier went into operation in 1986!).

Field reversals, occurring roughly every million years, are the most dramatic of the wide range of phenomena exhibited by the earth's magnetic field. And the next reversal on Earth may not be so far away: if the current rate of decay of the Earth's dipole component is maintained, it will vanish in less than 2000 years' time.
— Jeremy Bloxham, 'Evidence for asymmetry and fluctuation', Nature, 322: 13, 1986

Time

The poor world is almost six thousand years old . . .
— William Shakespeare (1564-1616), As You Like It, IV, i, 95

There are said to be a billion billion insects on the earth at any moment, most of them with very short life expectancies by our standards.
— Lewis Thomas (1913 – ), The Lives of a Cell, Penguin Books, 1978.

We can be certain that the radiation did not change appreciably during the last 500 million years; because during all this time life existed on earth, which means that the temperature of the earth during the whole period must have been very nearly what it is today. This temperature is determined by the sun's radiation.
— Hans Albrecht Bethe (1906-000), The Sky, December 1940.

More recently, advances in physics have given us methods to put absolute dates, in millions of years, on rocks and the fossils that they contain. These methods depend on the fact that particular radioactive elements decay at precisely known rates. It is as though precision-made miniature stopwatches had been conveniently buried in the rocks. Each stopwatch was started at the moment that it was laid down. All that the palaeontologist has to do is dig it up and read off the time on the dial.
— Richard Dawkins, The Blind Watchmaker, Penguin, 1986.
 
Slate blocks, Norway.
According to this view of the matter, there is nothing casual in the formation of Metamorphic Rocks. All strata, once buried deep enough, (and due TIME allowed!!!) must assume that state,—none can escape. All records of former worlds must ultimately perish.
— Sir John Herschel, Letter to Mr Murchison, quoted in the Appendix to Charles Babbage, The Ninth Bridgewater Treatise: A Fragment (1838), 240.

Fossils

… implacable November weather. As much mud in the streets as if the waters had but newly retired from the face of the earth, and it would not be wonderful to meet a Megalosaurus, forty feet long or so, waddling like an elephantine lizard up Holborn Hill.
— Charles Dickens, Bleak House, London, 1852, page 1.

Life has come to be regarded by the majority of biologists as forming one vast genealogical tree, the roots of which are buried deep down in the lowest fossiliferous strata, and the tops of whose branches, constituting the life that now exists on the globe, are alone seen above the surface.
— John Gibson, 'Fossil fishes of Scotland' in Science Gleanings in Many Fields (1884).
Fossils in marble, Sydney.


We are lucky to have fossils at all. It is a remarkably fortunate fact of geology that bones, shells and other hard parts of animals, before they decay, can occasionally leave an imprint which later acts as a mould, which shapes hardening rock into a permanent memory of the animal. We don't know what proportion of animals are fossilized after their death — I personally would consider it a very great honour to be fossilized — but it is certainly very small indeed.
— Richard Dawkins (1941 – ), The Blind Watchmaker, Penguin Books, 1988, p. 225.

David Davies, a Welsh mine foreman, was the first to make really large collections of plant material from different coal seams. He showed that even when the plants did not differ very much, there were differences in the proportions of different kinds, just as in one meadow you will find a great deal of clover among the grass, in another very little.
J.B.S.Haldane (1892-1964) Everything Has a History, Allen and Unwin 1951, page 50.
 
Fossils in a limy sandstone, W.A.
If a single well-verified mammal skull were to turn up in 500 million years-old rocks, our whole modern theory of evolution would be utterly destroyed. Incidentally, this is sufficient answer to the canard, put about by creationists and their journalistic fellow travellers, that the whole theory of evolution is an 'unfalsifiable' tautology. Ironically, it is also why creationists are so keen on the fake human footprints, which were carved during the depression to fool tourists, in the dinosaur beds of Texas.
— Richard Dawkins (1941 – ), The Blind Watchmaker, Penguin Books, 1988, page 225.

Soil

Erosion in a spoil heap, South Australia.
In the agricultural sense soils are the superficial layers, usually less than a foot in thickness, of disintegrated and decomposed rock material, which is mingled with organic matter, and furnishes the necessary conditions and materials for plant growth.
— G. W. Tyrrell, The Principles of Petrology, Methuen, 1929, p. 184.

As to the ground or soil, it is in general but very indifft — in some parts nothing but hard, solid rock, in others a black sand full of ant hills.  In some spots, however, it is better, in one place especially we have found some good strong clay of wh they have already begun to make bricks wh are said to be very good.
The Governor has taken several excursions inland many miles into the Country.  First a little to the Northward — here the ground and country are most wretched, nothing to be seen but impassable Rocks, thickets, & swamps.  Next he went more towards the S.W.  Here he met with better ground — also with blue shale, a thing likely to be of great service to the Settlement.  The wood is in general very ordinary & bad for building.
— George Mackaness (ed.), Some Letters of Rev. Richard Johnson, B.A., First Chaplain of New South Wales, 2 parts: Australian Historical Monographs, new series vols XX and XXI, Sydney: D.S.Ford, 1954, part I, page 19 (letter dated May 8, 1788). 

Some idea may be formed of the appearance of the country by what is seen on the South Head Road, near the Light House. At the distance of a mile from the Heads, the spectator comes to a spot from which he can behold nothing but rock blackened, with the effects of fire. Every tree, shrub, flower, or atom of grass, has been burnt to the very root; and accustomed as the eye is here to look with indifference upon large tracts of land around, with scorched and half consumed trees, one cannot contemplate the scenes we allude to without becoming sensible of an extraordinary sensation, produced by the air of desolation with which one is surrounded.
Cattle at this season are much distressed for want of water. The stockmen are obliged to drive them to the distance of many miles, even for the scanty supply which a small creek or rivulet affords.
The Australian (Sydney), 9 December 1826, 3.

Simulating sedimentation.
We are wealthy and wasteful but this can't go on. If we don't eat dog biscuits, we could end up eating our dog instead.
— Magnus Pyke (1908 – 1992)

Now I submit that we cannot say much which is sympathetic to our time unless we have assimilated our immediate tradition, which for this country is the conquest of soil and climate. Accordingly, it is a function of Biology in the University to provide this ingredient in education.
— Professor Eric Ashby, The Place of Biology in Australian Education, inaugural lecture, Sydney, 1939.


Climate and weather

In parts of Siberia the southern boundary of permanently frozen ground is receding poleward several dozen yards per annum.
— George Kimble, Scientific American, 1950.

While all the evidence goes to show that carbonic acid is now an almost invariable constituent of the air, it is one that requires least change in the physical conditions under which the earth exists to effect a change in its proportion. Minute as the proportion is, the delicacy of its relation to animal and vegetable life on the earth makes the maintenance of the apparently unstable equilibrium a matter of serious concern to mankind.
Scientific American, October 1883, quoted in Scientific American, October 1983, p. 11

Occasional droughts occur throughout the colony at periods varying from ten to fifteen years: and periodical floods of a destructive character have at various times caused a serious loss of life and property.
— George French Angas, Australia: a Popular Account, 1866, 140.

We live submerged at the bottom of an ocean of the element of air, which by unquestioned experiments is known to have weight, and so much, indeed, that near the surface of the earth, where it is most dense it weighs about one four-hundredth of the weight of water [actually more like 1/775]. Those who have written about twilight, moreover, have observed that the vaporous and visible air rises above us to about [80 kilometres]; I do not believe its height to be so great, since if it were, I could show that the vacuum would be able to offer much greater resistance than it does…
— Evangelista Torricelli, in a letter to Michelangelo Ricci, 1644.

Not that there is anything very mysterious ... if it is remembered that a barometer is merely a weighing balance under another name. Instead of weighing a letter or a parcel against a series of standardised weights, it weighs the whole mass of air above it, right to the top of the atmosphere, against a column of mercury. An area of high pressure … is the outward and ground-level sign of a mountain of air above. The mountain of air is heavy. So the mercury has to rise higher…
— A. W. Haslett, Unsolved Problems of Science, London 1937.

Attributed bits, lacking sources.

I could more easily believe that two Yankee professors would lie than that stones would fall from heaven.
— Thomas Jefferson (1743-1826), in 1807.

I agree. But I wonder what it would have looked like if the sun had been circling the earth.
— Ludwig Wittgenstein (1889-1951), on being told how foolish the ancients were for accepting the Ptolemaic system.

My own suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose.
— J. B. S. Haldane (1892 – 1964)

The most incomprehensible thing about the world is that it is comprehensible.
— Albert Einstein (1879 – 1955)