My entry for the Dear Friends letter 2016

2016 was a good year for me. One of the many highlights for me this year was Geocaching. Geocaching is an international sport which consists mainly of finding hidden boxes in the woods with a GPS(Co-ordinates are posted online). I found out about the game in April this year, and since then I have found 51 geocaches with my phone. I got to most of them on my bike and some of them on family trips and vacations, including trips to the Netherlands and Singapore.

Sailing season is around Summer(October-March in Australia), so this year had parts of two sailing seasons. The first, when I went to the Royal Queensland Yacht Squadron in Manly, QLD, started in late 2015. During that term I completed the Tackers course, which teaches basic knowledge of sailing for children. I needed the certificate from Tackers to get into Green Fleet(higher level teaching, including the rules of racing). I sailed in Green fleet through the beginning of 2016 and up until March. By then, the sailing season had ended, and I finished Green Fleet and was allowed to sail in a higher level group, Intermediate Fleet(also called Blue Squadron) during the next season. Unfortunately, sailing in Intermediate Fleet required owning a Laser at the sailing club, which are very expensive. Because of this, I had to start sailing at another club the next season.

Starting at October, I sailed at the Humpybong sailing club at Redcliffe. Since I had completed Tackers, I was able to get straight into Green Fleet. Because there are no higher-level courses at Humpybong, the next step was to become a Tackers assistant instructor. I enrolled in a two-day course back at Manly and got an AI certificate. The course I will be helping with will be in early January.

Meanwhile, I had been reading many books with Steve every evening. This year we finished The Grapes of Wrath by John Steinbeck, we read Much Ado About Nothing by Shakespeare, which we watched with my grandmother, and we read Catch-22 by Joseph Heller.

I have also been practicing clarinet regularly and have passed the grade 3 music examination for clarinet. I am now working on some pieces of music for two auditions which are both scheduled mid-January.

One of the biggest highlights for the year was the trip to the Netherlands. As it started, eight time zones of air travel made August literally the longest month of my life(and September the shortest). We switched to a connecting flight in Dubai on the way and saw some of the airport. A few days after we got to Leeuwarden, capital of Friesland, we took a ferry to Terschelling, our favourite island. It is a small island, only 30km long, and I had a lot of fun biking around the island and seeing the nature, the towns, the farmland, and the ruins of German WWII bunkers. After staying there for 3 weeks, we went south to the city of Nijmegen, stayed there for a few days and went around to an amusement park and the German border. Then we went back to Schiphol and flew to Singapore. We stayed there for 3 days and then returned to Australia. It was the best trip I had in 4 years.

Lost World

The Gold Coast is a weird place. Lots of beaches, lots of sunlight lots of high rises, no hills. It's kind of well known in Australia for being the Australian equivalent of Miami -- lots of high rises against the beach, inhabited by both rich and poor. People go there for vacations, or just to say they've been there. Like I said it's a weird place. On the Southern end of the Coast rises a series of low hills. These hills, which are low and fairly unpromising, rise quickly into a landscape which bears no resemblance to the strip malls and big houses below. Protected by the Lamington and Springbrook national parks, the landscape traces the border and is called the McPherson Range.

Many explorers have tried hard to map the area, but the McPherson Range is the size of Rhode Island and much, much more impenetrable. Who knows; there might be undiscovered plants and animals in the area. The first road to lead into the area led to O'Reily's, a rainforest guesthouse that still stands today. Nowadays, many tracks and roads cross the range and we went on one of them to reach Green Mountains.

Green Mountains is the part of Lamington National Park that surrounds O'Reilly's. It contains some of the most mountainous, inaccessible rainforest in the entire park. The road to O'Reilly's, which has not changed route or width since it was built, is a one-lane road with many blind curves which looks like spaghetti on a road map. On the way there, the road even leads through a long, squiggly one-way cutout to get past a series of cliffs! We spent a very brief time in the Mountains -- two days. But during that time we saw a lot of the park, and really got a feel for what the mountains were like.

The morning after arriving, I and my dad and my brother set off for an extended hike: the Albert River Circuit, a seven hour hike that did most of the walking far away from the Green Mountains campground. We got up early to do the hike. There was no trail that led from the campground, so we walked along the road and past a parking lot to get to O'Reilly's. The O'Reilly's lodge has changed a lot since it was built, and it is now the centre of a large clump of hotel buildings, a cafe' and a souvenir shop. The O'Reillys still own it, though.

Across the road was the main trackhead, at a sign declaring that we had just arrived at the Border Track, a long trail connecting Green Mountains to a distant trailhead, Binna Burra. The Border Track is very well maintained for being the starting point of most day hikes in Green Mountains. We walked easily along the hard clay path before seeing a land mullet. Land mullets are a very large species of skink. This one was so big, I could have mistaken it for a baby crocodile if it had spikes on its back.

We continued to walk past intersection after intersection, always going straight ahead. The trees are gigantic in Lamington. Giant figs coated with vines and epiphytes loomed out of the green haze of the tree ferns. Vines were everywhere, and wherever there weren't vines there were cliffs. No small wonder explorers took so long to get this far. As the downhill slope on our left got steeper, I could sense a gigantic chasm to our left side, much deeper than it was wide. Both up and down, the slope went on and on without end. It was like we had shrunk to the size of insects, or like a small valley had grown to the scale of the Grand Canyon. Everything was much, much bigger than it should have been.

After an hour and a half of walking, we passed a gigantic Antarctic Beech -- so named for the place it was first identified, as a fossil -- and reached the beginning of the Albert River Circuit. We left the main trail on the right and followed an overgrown track, dodging fallen trees as the track narrowed. The Albert River flows on the next valley over from the Border Track, so I had expected to top out onto the ridge top between the two valleys. We never did. Instead, we contoured across the slope as it got steeper and and the path got surrounded by cliffs. For the whole time the track was doing this, I never suspected that we were slowly turning to the right, slowly winding around a mountain peak. Until the track switchbacked and it was obvious we were in a different valley than we started in.

The walking book we had (which was fairly outdated and may not have taken into account a track closure) told us we would reach the first waterfall of the track, Jimboomba Falls, about half an hour after turning off the Border Track. It was full hour and we had not even seen a creek yet. Then suddenly, we turned a corner and crossed a dry creek bed. Stupidly thinking this was Jimboomba Falls, we kept walking and then saw something totally weird. It was a lobster. Except it was crawling along dry ground far from a flowing creek. And it was blue and white. I don't know why -- I mean, it was just a lobster -- but it weirded me out. I learned later that this was a Lamington Spiny Crayfish, a freshwater yabby endemic to the Mcpherson Range between Tamborine and the Main Range.

Excited about the find of the crayfish, we walked easily to what was actually Jimboomba Falls to have a snack. The falls were just a small cascade, but they were interesting to see partly because thick moss growing on the sides made them look otherworldly. After checking for leeches we continued on a steep zigzag downward, sometimes clinging onto cliffs to avoid slipping and falling. Often we would have glimpses of the creek, which was always pouring over a high waterfall. At the end of the zigzag, we crossed the creek with glimpses of Lightning Falls -- a very high, free falling waterfall.

Earlier we had not been following the Albert River, but an offshoot called Lightning Creek. Just after Lightning Falls, we descended to the river itself. It was big, about five times as big as Lightning Creek. The first waterfall we discovered on the river was Mirror Falls. Mirror Falls was the most beautiful, mainly because of the mossy walls on either side of it. We passed four other, not very impressive falls in quick succession, before arriving at Echo Point Lookout which altered my view of the place completely.

Descending down to the creek was steep, but climbing back up was along more or less flat ground. Then we headed along a sidetrack to the lookout. Before I even arrived I could sense a void ahead of us, like we were standing at the edge of the Earth. In another minute we practically were. The Escarpment, which traces the New South Wales-QLD border, is a massive crescent shaped cliff that drops steeply and almost vertically about a kilometre into the plains below. We were standing on its edge, from which we could see the hulking ramparts of Mount Warning, the Border and Nightcap Ranges and even Byron Bay and the entire Gold Coast. It was the best view I have ever seen in SEQ, hands down.

We zombie walked for two hours back out along the Border Track, collapsing at what I hoped was a cafe'. It was the start of a treetop walk. Normally I don't like treetop walks -- I mean, they seem to be everywhere and I'm sick of them -- but this walk was pleasantly rickety and seemed like it would fall apart at any moment. I really liked it. We spent some time there, then walked back to the tents and collapsed.

If you are interested in walking the Albert River Circuit, or just want to know more, someone made an interesting video about it. A link is provided here.

The walks of the following day were done with another family who were friends of us. Since we had little time and energy left, we chose short walks around the area. The first one, to Python Rock, gave us a spectacular view over the mountains and really revealed how deep the gorges went. I would say they were about as big as Grose Gorge in the Blue Mountains, possibly bigger. Then we went on another walk, to the top of Morans Falls. But as we were arriving at the top of the waterfall, the sky broke apart and a torrential downpour began. Using any convenient track to get us back to safety, we ran up a muddy track labelled "O'Reilly's".

Suddenly, we emerged on an old gravel road. Not knowing where to go we just went right and found an old wooden shack. We raced to get under the eaves. Suddenly, Dad called to tell us the door was unlocked and we scrambled in. An information board revealed it to be an old slaughterhouse. My dad, I and my little brother were here, but no one else was, so we just sat inside and waited.

After twenty minutes the rain stopped. Noting that nobody had arrived yet, we just got out and walked along the track ourselves. Leaving the road to follow a promising looking track, we walked through a picturesque rainforest on a windy path that went through several large gum trees. Finally, we emerged at O'Reilly's where we met the others, sitting at a cafe'. They told us they had taken a different track, and had been waiting for us for half an hour.

Lamington is not the most amazing place in the world, or even Australia. But it is a great place and a must visit for anyone living in or visiting South East Queensland.

Girraween

In this article I am going to relate to my experiences in the Girraween area -- both on the most recent trip and on one I did, a year back, with Scouts.

The Girraween is by any measure an amazing place. While its largest granite outcrop -- Bald Rock -- is a fraction of the size of Uluru, the Girraween area gives you a sense of beauty that Uluru and the nearby Kata Tjuta lacks. Furthermore it is much closer to Australia's cities, being a mere three hours drive from Brisbane in Queensland's Granite Belt.

What does the place look like? The Girraween is located on top of a high plateau. A visitor to the valley below would never suspect it was there, if the signs were taken away. The top of the plateau is a large, undulating landscape, unremarkable except in one way: the rocks. They puncture through vast ribbons of eucalypt forest like needles, standing high above everything else but each other.

My first summit of such an outcrop was the climbing of South Bald Rock, a dome of granite that looks vaguely like a bald man's head. It happened on a Scout hike a year back. South Bald Rock is no moderate peak, approaching a height of 150 metres relative to surrounding plains. From the top we could see all the other peaks from a 360 degree view. To the immediate West lay the West and Centre bald rocks, then the rocky rise of Mount Norman that all but obscured Turtle and Castle Rocks, the Sphinx, and the Pyramids. To the East the view was more breathtaking: we could see Bald Rock, but behind it was a continuous ribbon of undisturbed forest that culminated in the gray spire of Mount Barney -- which was 90 kilometres away and should have been out of sight. Due to the curvature of the Earth, Mount Barney looked lower than us.

After that initial trip to the Girraween I vowed to return, and I finally did in October of this year. Not with Scouts this time, but in a family trip with friends. In Scouts, we completed the Eastern Peaks Circut: a lengthy hike involving climbs on the eastern (New South Wales border) side of Girraween National park. This time, we would visit the more built-up, western side of Plateau. Here was a visitor's centre and even a campground.

We were fairly ambitious on the first day, making a visit to the First Pyramid. The name of the Pyramid was inspired by its shape: a three or four cornered dome, tapering slightly at the top. To get to the summit we ascended a granite surface sloped at fifty degrees and smooth as glass. When we got to the top of this slope, we turned the corner and found the trail following a natural catwalk. Although the surface of rock was only tilted at thirty degrees or so, it tilted sharply toward a void I did not want to end up slipping into. My hands became shaky as I began the traverse, and I collapsed when I got to the other side.

The base is smaller than it seems.

We continued to the summit. The true summit was inaccessible as it was on top of a boulder, so we continued to a natural rock platform, from which we could see the climb route. Rather than sweeping 360 views we were promised by faraway views of the mountain, the view was dull and obscured by boulders. Still a good view, though. Then we scrambled to a viewpoint on the other side of the summit, which looked down upon another mountain: the Second Pyramid. It was weird, like a gigantic pudding dropped in the middle of the forest, and was completely devoid of trees or even subsidiary boulders. On the way back, we passed a boulder three times the size of a house yet balanced on a base the size of a dinner plate.

It was getting dark so we returned to the campsite.

The second day was much better. After some decision, we decided to walk to Turtle Rock.

Turtle Rock is a low dome of granite we saw from the Pyramid. It looks just like a sleeping turtle. Next to it is the Sphinx, a needle-like finger of rock poking out of a boulder field. The walk was supposed to take four hours, but we took five because we were exploring so much.

The walk began by climbing up through open eucalypt forest and scattered boulders. At long last, we got to the top of a ridge and followed it to the Sphinx. The Sphinx itself was not very impressive, but we spent an hour exploring the massive boulder field on all sides of it. A short walk brought us to the base of Turtle Rock. To get to the top, we scrambled up through a narrow gully. Then, just above a ledge with good views of The Sphinx, we were blocked from going further by a 5m cliff.

The turtle

The Sphinx and Turtle Rock from Castle Rock

I thought it was impossible to go further, but after some searching I found a slot crammed with boulders. If I scrambled along the boulders and chimney climbed through the slot, I could just make it. I did so. The going was hard though, and I almost got stuck twice. But I got to the top of Turtle Rock and was rewarded by 360 degree views.

On the return trip we climbed Castle Rock. It was much less exposed than The Pyramid and had much better views. After having climbed the mountain, we called it a day and retreated back into our tents.

Note: None of these pictures are ours.

Our final objective was Underground Creek. A short walk from the car park, Underground Creek was a creek that carved an overhang, which promptly buried the creek when it collapsed. Brave souls still venture into the cave below the overhang, to find the creek and more.

After thoroughly exploring Underground Creek, we set off for an offtrack adventure to find the fabled Aztec Temple (it's actually a jumble of boulders). We tried, and got as far as the ridge it sits on before turning back due to casualties.

The failed Aztec Temple expedition reminded us of how much we had not seen in the park. We will need to go back here sometime. As we drove home through the Main Range, I was reminded of how much there is to see in the world, and how we can only hope to see a fraction of it in our lifetimes.

The fabled Aztec Temple.

Neutron

There is a recipe in the back of Edward Lear's Book of Nonsense which begins like this:

"Procure some strips of beef,  and having cut them into the smallest possible slices, proceed to cut them still smaller, eight or perhaps nine times."

The recipe raises some interesting questions such as: What would these tiny pieces of beef look like? Is it even possible to slice anything past the molecular level? There is another question I am more interested in. If you slice things into small pieces, they take up less space. Could you eventually make things disappear entirely, just by slicing them?

As a matter of fact, it is fairly easy to break apart molecules; your body is doing it now. Atoms are more tricky, but scientists have split the atom more than seventy years ago. You rely on atoms fusing together in the Sun, after all. To answer our first question, the beef wouldn't look like beef past the molecular level. In fact, if you managed to split apart every single molecule in a slice of beef at once, it would trigger an explosion as the oxygen fuses to form the kind of air you breathe. (if you did the same thing to atoms, you would make a large nuclear explosion.)

Of course, it takes some pretty tremendous forces to split atoms. The only place where it is done on a big scale is in the core of a large star, when it dies. If a star is much bigger than our sun, it struggles constantly to stop collapsing in on itself.  The star relies on fusing atoms to survive. The moment a star runs out of fuel, its inner layers collapse. The outer layers of the star crash into the inner layers, and rebound into space in what is known as a supernova. What is left is the core. In a Sun-sized star, the core left is a white dwarf, which glows for a while before winking out. However, in a large supernova, the atoms are so strained by gravity they split apart and form an extremely dense and often quickly spinning object known as a neutron star.

Neutron stars are really strange things. They can be the size of cities but the mass of the Sun. They are mostly made of neutrons. Many have a fragile 'crust', which can fracture and create terrifying power surges. Some orbit a star, which they suck power from. Sometimes neutron stars merge and create massive bursts of light. Some neutron stars, known as pulsars, spin several times a second and emit energy from their magnetic poles.

Most weird aspects of neutron stars come from their incredibly small size and their amazingly large amount of mass. There is a type of object which has even more mass and a smaller size than a neutron star: a black hole. Black holes are made by splitting the components of atoms apart into individual quarks. Black holes are really weird. They are objects with a gravitational field so extreme, they can bend light. You cannot even see a black hole; you just see, well, a black hole. Around a black hole, time slows down and everything is redshifted. We barely know anything about black holes at all. All we know for sure is that they are unimaginably small and dense.

I wish there was a way to split quarks - the components of neutrons and protons - apart, but there isn't, as far as we know. And finally we arrive to the answer of our third question: It is not possible to cut a slice of beef into nothing, but you can make a black hole.

Cultures

I noticed a lot of things in Switzerland that were not in Australia, America, or even northern Europe. One of them was the mountains. Australia's highest mountain is a mere hill compared to even the lowest mountain in Switzerland. Even the Rockies are no comparison to the mighty Swiss Alps.

However, the mountains were not what struck me most about the country. What struck me most was its culture.

The culture of an area is its identity. If someplace has a very old, established culture, it becomes instantly recognizable if you happen to be there. Australia was never properly populated before the Industrial Revolution, so its culture was mostly stolen from other continents; in Europe, however, country and even regional borders are obvious.

Let's take Italy and Switzerland - the two countries I visited this July. These two places, although neighbors, are shockingly different. One has been neutral for the past hundred and fifty years; the other has been heavily involved in both world wars. One has had a long history of organized crime; the other is one of the safest countries in the world. One makes great cheese; the other makes even better pizza. When I visited Italy on a day trip, the border between the two countries was obvious. It was marked on a pass by two massive stone eagles (a memorial of some battle victory in the Napoleonic Wars). To the north, there was a valley and beyond that, icy snowcapped mountains. In the valley there was a town with a visible church. The town seemed to have no center; it was stretched out across the valley floor. To the south, in Italy, the mountains tapered off abruptly and gave way to rolling hills, all sparsely covered with houses and lakes.

Cultures are interesting in the way that they carry on even when the geography that shapes them does not. For example, in Switzerland, there are two geographic regions: the Swiss Alps and the Rhineland. In the Swiss Alps, where Switzerland was first created, there is almost no flat land at all, except for that thin ribbon of farmland at the floor of each valley. As a result, all towns have only one road of any importance and the shops are spread out over hundreds of metres, sometimes kilometres. Curiously enough, when Switzerland grew to encompass the Rhineland, the system carried on. Look at a map of any city established under Swiss rule and you will see a distinct linear pattern.

My favorite thing about Swiss culture is the architecture. Architecture varies greatly all over the world. Even if a region has none of its own food, town layout or traditions, it will have its own architecture. Swiss houses and hotels have strange roofs for a place with a lot of snow; they have almost vertical outer sides and very flat tops, like boxes. Not all of them do of course; it's different in every single valley, just like the food and many other things are. And that's what I like most about Swiss culture: its variation.

Invisible light

We perceive the world in the three colors that our eyes can sense- red, green and blue. This gives us a visible range of all of the wavelengths in between 390 and 750 nanometers. However, there are wavelengths in the infrared and the ultraviolet that, if viewed by a special camera, can reveal much more about the world than our eyes can. I am working on a project to build a new type of these cameras. In the following paragraphs, I will explain more about how they work and about the one I built.

Cameras that can see past red and past violet are called multispectral cameras. These cameras can be mounted on satellites to view natural features and cities in a way that no ordinary camera can. There are many different regions of the spectrum, most of which can only be seen with the aid of such a camera. The ultraviolet is mainly used to photograph biological compounds, while the near-infrared has a wide range of applications. The near-infrared is a band of wavelengths that is just beyond red. It ranges from 750 to up to 1400 nanometers. Even though this is beyond visible, these wavelengths are still extremely small- up to 1.4 times a thousandth of a millimeter.

The way to reveal the most about an object using multispectral imaging in the near-infrared part of the spectrum is to filter out one wavelength at a time. However, technology that can do this is very expensive. This is why I am working to make a cheaper multispectral camera.

Instead of filtering incoming light into different wavelengths, this camera works by having both the camera and the object inside a box to block out all other light, and illuminating the object with LEDs that emit light in various wavelengths in the visible and near-infrared parts of the spectrum. Both the LEDs and the camera controlled by a type of small computer called a Raspberry Pi. The computer is programmed to flash each color of LED in succession while taking pictures with the camera. This way, the images can show how an object reflects and absorbs different wavelengths of light individually. This method is cheaper, and its only limitations are the spectral range of the camera and the variance of the LED colors.

For the programming of the camera, I used a programming language called Python, with which I was able to write the programs for the operation of the camera over an internet connection with the Raspberry Pi. One of the problems I faced was how to make a Printed Circuit Board(PCB) that included places for all of the LEDs so that I could solder them. I did this with a program called gschem.

The type of multispectral camera described above can potentially have many uses in agriculture. It would be able to detect bruises on fruit and possibly detect when it goes rotten much faster than human eyes can. It could also detect diseases in plants. In conclusion, multispectral cameras can be very useful to help us understand the world we live in more fully.

References:
https://en.wikipedia.org/wiki/Multispectral_image
https://en.wikipedia.org/wiki/Near-infrared_spectroscopy

Grain of Sand

It is no wonder that geologists swarm to the Jack Hills, Western Australia -- for it is the site of the oldest rocks on Earth.

There are larger old rocks in Canada, but they are 500,000,000 years younger than the Jack Hills rocks. There are older meteorites in Antarctica, but they were not formed on Earth. The rocks at the base of the Grand Canyon -- thought by many to be the oldest rocks on Earth -- are a whopping 2,650 million years younger than the rocks of Jack Hills.

Being about 4.4 billion years old, some rare Jack Hills sand grains came from the first rocks Earth ever had. However, the old rocks of the Hills are just that: a few very rare sand grains, called zircons, which are deeply embedded in sedimentary (made of sand) and very metamorphic ('changed') rocks. How did these tiny grains appear here in the first place, and how might they have survived the wear of time? Why are they so rare in the first place? Let's go back in time to find the answer.

The Crust Solidifies

4.4 billion-years-old Earth is not a place you would want to live. A human, dropped on the prehistoric planet's surface, would be fried by nuclear radiation, burned by lava, choked to death by poisonous gases, and crushed by meteorites within the first five minutes. One good thing about early Earth: Oceans. Scientists have found out that the Jack Hills zircons were created in water; water which could have come either from meteorites or the planet itself. In any case, Earth had oceans, but still wasn't cooled enough for the igneous rocks to turn into anything else, whether sediment or metamorphic rock. Also, there was virtually no oxygen. This meant, for now, that the early rocks were safe from change. That is, until . . .

Life Begins

Life is currently thought to have originated around 4.0 or 3.9 billion years ago. The oldest evidence for life comes, like the earliest evidence for water, from those same Jack Hills sand grains. Life did not have much effect on early rocks until about 3.4 billion years ago, when the Earth had cooled down significantly and erosion had begun creating the first sedimentary rocks. Around this time, moss-like cyanobacteria began making the first stromatolites (crazily, the only colony of stromatolites left is within sight of the oldest rocks). Cyanobacteria use photosynthesis, a complicated process which turns carbon dioxide, water, and sunlight into sugar and oxygen. The latter was released on a massive scale into the atmosphere. This would not have been that bad, but there was a lot of iron in the volcanic rocks. The oxygen and iron combined to form rust, and immediately the age-old rocks from Earth's creation began to fall apart. Jack Hills zircons, not being made of iron, had survived for the time being. However, an important factor was now coming into play . . . .

Radiation

There were trillions of trillions of zircons on Earth when it was first created. Corrosion and heat did not change their numbers very much. However, around three billion years ago, the zircon crystals began to break apart, due to a process known as metamictization.

Early Earth was very, very radioactive. Rare elements today, like actinium, used to be very common four billion years ago. Uranium-238, the most common radioactive element, has a half-life of about 4.5 billion years. This means that a 200-atom sample of uranium from the creation of Earth would have about 100 atoms now (the other atoms would have turned into something like radium). A by-product of radioactivity is radiation, in this case in the form of alpha particles. You may expect a zircon to have had about a million atoms of uranium in it 4.4 billion years ago. By now, the decaying uranium would have released at least 500,000 alpha particles -- more because what uranium decays into, decays into something else. 500,000 alpha particles are more than enough to destroy the crystal.

A few, very rare zircons would have survived long enough to endure the next test.

Plate Tectonics

In 2013, scientists were shocked to recognize the remains of a massive continental plate, lodged deep within the Earth underneath North America. This plate was called the 'Farallon Plate', and was later discovered to have been shoved underneath the crust by the Pacific and North American plates.

As shocking as it may be, it is not uncommon for a continental plate to slide underneath the crust, never to come back again. It has happened throughout the history of the Earth since plate tectonics began, around 4 billion years ago. Every 300 million years or so, the Earth's crust is recycled. Our zircons could hold out under the immense pressures of the Mantle for a while. Eventually, however, even the strongest crystal on Earth could not survive.

What saved our zircons is exactly what destroyed all the old rocks: Erosion.

The zircons, swept by the wind, would have spread across the world, minimizing the chance of all being destroyed. They would become part of normal sandstone rocks, which would erode and the zircons would have been released again. Nevertheless, the oldest zircons became rarer and rarer. Finally, around 600 million years ago, a group of zircons became embedded in some sandstone rocks. Eventually, as most of their neighbors were slowly destroyed, the last zircons got buried under heaps of volcanic rock. The surrounding land went through cycles of burial and erosion, but the zircons were protected by the volcanic rock. After being warped by pressure, the sandstone containing the zircons slowly, but surely, was uncovered. It was now part of the western Australian plate.