The Orange Skin

Written by Adam Martin

The hour the rock burns

AT THE FIRST BLUSH OF morning, when the sun hauls itself dripping from the Tasman Sea and spills its light low and level across the water, the granite of Bicheno begins to burn. It does not burn as fire burns, with hunger and haste, but as an ember burns, slowly and from within, so that the great rounded boulders heaped along the shore: from the Blowhole, past the Gulch, out towards Peggy’s Point, seem to surrender some ancient warmth they have hoarded through the long vigil of the night. There is the apricot hue of the rock, the white lace of the swell, and the black, glistening band where the sea last laid its hand. And above that black band, laid over the rock like rust upon a ship’s weary hull, like pollen upon the legs of a bee, there is the orange, blazing into the overture of another day.

People travel the world to stand before it. They crouch with their phones and frame that copper fire against the basalt and turquoise; they lean their children against it for photographs, and they lay their palms upon it as one might rest a hand upon the flank of some slumbering creature, uncertain of what they touch yet certain, with a quiet and wordless awe, that it is something. Ask them the colour’s provenance, and they will speak of iron bleeding from the rock, of a mineral stain, of some species of moss.

It is none of these things. The orange is alive. It is a lichen, a creature so enigmatic that for most of humanity’s long history we failed to comprehend its nature, and even now those who devote their lives to its study confess, with a humility I find strangely consoling, that they have scarcely begun. And the grey rock beneath it is not old in the gentle way we speak of grandparents and cathedrals. It is old in a manner that undoes language itself, so ancient that when it was born there was no flower upon the Earth, no blade of grass, no bird, no bee, and the first forests were only beginning to rise from the primeval swamps of a world we would not recognise.

This, then, is the story of two things pressed together, skin to skin, upon a temperate coast at the bottom of the world: a rock forged in fire nearly 400 million years ago, and a living rind that has painted it, in the place where you now stand, for only the last few thousand. To understand why that copper dust gathers here, and why it gathers with such extravagance, we must return to the beginning, and the beginning lies a long way down, beneath the ceaseless tides of time, in the dark and molten heart of the Earth itself.

A fire that never reached the sky

LET’S TRAVEL BACK TO THE DEVONIAN, close to 400 million years ago, in an epoch so remote that there was no Tasmania, no island, no Bass Strait, nothing a cartographer of our age could have named. The ground that would one day become Bicheno lay along the ragged eastern margin of Gondwana, that vast southern supercontinent, and it was not ground at all, but a deep accumulation of sand and mud settled upon an ancient sea floor. Geologists call these sediments the Mathinna beds. In the age of which we speak, they were being compressed and buckled and folded like a rucked rug, as the Earth’s crust convulsed in a protracted mountain-building upheaval that geologists, with their unfailing gift for the unlovely word, call the Tabberabberan Orogeny: a name that sounds less like the birth of mountains than a nasty cough you ought to go and see the Doctor about.

Deep within that crumpled crust, rock surrendered to the heat and melted. This was not lava. It was magma that would never behold the daylight, born of older rocks, some once molten themselves, some once humble mud, partly melted and remade. Lighter than the rock that imprisoned it, the melt ascended in vast, unhurried bodies the size of mountain ranges, shouldering its way upward through the folded sediments until it stalled a few kilometres beneath the surface. And there, in darkness and in pressure, across a span of time beside which a human century is but the brief flare of a struck match, it cooled, a slow sonata played out in the silent depths of the world.

That patience is what made it granite. Lava that pours across the surface freezes swiftly and finely, its crystals scarcely begun, but magma sealed away beneath the Earth cools so gradually that its minerals have time to find one another, and to grow. Bend close to a Bicheno boulder, and you may read that patience written in the rock. There are pale, blocky crystals of feldspar, some as long as the top joint of your thumb, set like sugar lumps within a coarser mass, and there is the grey glass of quartz, and the black flakes of biotite mica that glitter whenever the sun’s roving gaze alights upon them. In places there are dark knots of biotite and tourmaline, and white seams of quartz where the last hot fluids of the cooling body forced their way through its fissures. Geologists know this rock as the Bicheno Granite, one member of a family of kindred intrusions they call the Boobyalla Suite, and they describe its texture as porphyritic, which is simply to say that the great crystals grew first and the rest of the rock settled around them, like a congregation gathering about its elders.

It was not alone. For something like twenty or thirty million years, pulse upon pulse of magma ascended beneath what is now eastern Tasmania, and the legacy of that long subterranean symphony is a seam of granite running from Wilsons Promontory in Victoria, down through the islands of Bass Strait, along the east coast through the Bay of Fires and Bicheno and onward to Freycinet. The pink granite of Coles Bay, just along the coast, has been dated by the uranium locked within its minuscule zircon crystals to around 388 million years. The Bicheno rock belongs to that same Devonian kinship, born of the same slow fire, a sibling sentinel woven into the same boundless tapestry of deep time.

Yet a granite born kilometres underground cannot be touched until all that lies above it has been taken away, and that labour consumed most of the time that has passed since. Rain, frost, river and wind worked at the overburden grain by grain across hundreds of millions of years, through the reign of the dinosaurs and beyond it, through the sundering of Gondwana itself. Even the Tasman Sea that now beats against Bicheno is, by the granite’s venerable reckoning, a newcomer, opening only about 80 million years ago as the land that would become New Zealand drifted away into the east, leaving this rock to face an ocean it had never known.

And as the weight was lifted, the granite began to crack along the joints that had formed as it cooled and contracted. Groundwater seeped into those cracks and slowly rotted the rock from its edges inward, turning feldspar to clay and leaving rounded cores of hard, fresh granite wrapped in a shroud of crumbling, decayed rock. Geologists call these cores corestones. When the soft and rotten granite was finally stripped away, the cores were left standing in the open air as boulders and tors, so that those great smooth forms heaped along the shore at Bicheno, which seem to have been polished by the sea, were in truth first rounded underground, in the dark, long before they ever felt the sky’s embrace. The sea has merely completed the work, and the orange, in the long procession of the ages, has come last of all.

A marriage made on rock

LAY YOUR PALM UPON THE orange, and you touch not one living thing but at least two, bound together so intimately that for most of history no eye could discern the seam. One is a fungus. The other is a microscopic green alga, a single cell capable of what the fungus can never achieve alone: the quiet alchemy of taking sunlight and air and water and transforming them into sugar. The fungus builds the house, a crust of interwoven threads that grips the rock, drinks the dew and gathers whatever minerals the world allows to fall upon it, while the alga dwells within, a few cells beneath the surface where the light may still reach it, paying its rent in sustenance. The fungus is so utterly bound to its tenant that it cannot survive without it, though the alga, some lichenologists believe, might yet manage on its own. It is a marriage, then, tender and enduring, though not quite an equal one.

We did not always understand this. For centuries lichens were filed away among the mosses and liverworts, humble grey and golden scurf upon rocks and roofs and trees. When the Swiss botanist Simon Schwendener proposed in 1867 that a lichen was in fact two organisms living as one, many of the eminent lichenologists of his day dismissed him, for the received wisdom held that every living thing was a sovereign individual. It took until 1939 for a scientist to pull a lichen apart into its partners and then reassemble it, and even now this enigmatic creature guards its secrets, for in 2016 researchers discovered that many lichens harbour a third partner, a yeast, which had hidden in plain sight through a century and a half of patient microscopes.

The orange lichens of the Tasmanian coast belong to a great and gaudy family called the Teloschistaceae, and to a group known in English, with rare poetry, as the firedot lichens. For a long time nearly all of them were heaped together into a single genus, Caloplaca, which swelled to more than a thousand species, until in 2013 a team of Scandinavian lichenologists used DNA to break it apart into dozens of smaller genera. The orange of the Bay of Fires is often said to be Caloplaca marina, a name borrowed from the orange belt of northern hemisphere shores, but the truth is that pinning a name to any one boulder’s colour is the work of microscopes and chemical tests, and a single rock may carry several species living side by side. The Tasmanian Herbarium, which has devoted more than four decades to these organisms, state that they discover at least ten lichen species new to science every year, and that is in Tasmania alone, a humbling reminder of how much of our own island remains, even now, unknown.

What renders them orange is a family of pigments known as anthraquinones, chief among them one called parietin. The fungus lays them down as minuscule crystals in the outermost skin of the lichen, where they serve as a sunscreen, absorbing blue light and ultraviolet before they can scorch the delicate alga beneath. The making of these pigments is awakened by ultraviolet light itself, so that the harder the sun’s gaze bears down upon a lichen, the more of its colour it creates. Biologists tracing the family’s history believe that about 100 million years ago, in the Late Cretaceous, the ancestors of these lichens forsook the shade of tree bark for open, sun-blasted rock, and that it was this orange armour that allowed them to do so and then to spread across the dry and exposed places of the world. Scientists long puzzled over how they manufacture such quantities of a toxic pigment without poisoning themselves, and have only lately glimpsed an answer.

So the colour that halts people upon the rocks at Bicheno, the colour they photograph and send to strangers on the far side of the planet, is not mere decoration. It is a parasol, a shield, a hymn of endurance sung in pigment, the visible testament of a life lived in the full and unforgiving glare of the southern sun, and it burns brightest precisely where that life is hardest.

The slowest clock on the shore

ASK HOW OLD THE ORANGE is and the honest answer arrives in two parts, much like the lichen itself, each part a different measure of time’s unhurried passage across the rock.

The first part concerns the crust before you. Lichens are pioneers, among the first living things to settle upon any bare surface, yet they settle in no hurry. A spore drifts in upon the wind and must find the right alga to marry, or a minuscule fragment carrying both partners lodges in the hairline fissure between two crystals of feldspar, and then it waits. A lichen cannot hold its water as a plant can, so that when the sun and the north-westerly dry the rock, it dries with it, utterly, and falls into something akin to suspended animation. When the dew settles, or a sea fog rolls in, or a heavy swell flings its spray up the granite, it drinks, wakes within minutes and resumes the quiet business of living. It can grow only in those hours when it is both wet and lit, and across the long procession of a year, those hours amount to astonishingly little.

Thus the crust-forming lichens, which press themselves flat against the rock, are the slowest-growing of all lichens. In a kindly place a crust might widen its edge by a millimetre or two in a year, and in a harsh one by far less. In the high mountains of Colorado, a common yellow-green map lichen was found to spread about fourteen millimetres in its first century of life before slowing to little more than three millimetres in each century thereafter. Do that arithmetic with the boulder before you. A single patch of orange the breadth of a dinner plate, spreading outward from one point at a millimetre or two a year, has been at its patient labour for somewhere between sixty and a hundred and forty years, the span of a human life and often longer. The broad, continuous sheets that cloak whole boulders are many such colonies grown together, their edges meeting and merging, the old centres often dying and flaking away while the margins press onward, so that a lichen may be older than any part of it you can touch: a living thing outlasting its own body, like a melody that survives every singer who has ever carried it.

That slowness has made lichens into clocks. In the middle of the last century the botanist Roland Beschel realised that the size of the largest lichen upon a rock could reveal how long that rock had lain bare to the sky, and from his insight arose an entire method, lichenometry, used to date the moraines abandoned by retreating glaciers. No one, as far as I can discover, has set such a clock ticking upon the Bicheno granite, yet the principle holds, and every orange disc upon that shore is a slow sundial, silently counting the years since it began, a minuscule chronicler of the seasons as they wheel past it into eternity.

The second part of the answer concerns not the crust but the band. No single thallus there may be more than a few centuries old, but the orange belt itself, that living stripe drawn at a fixed height above the sea, has renewed itself upon this coast, crust after crust, generation upon generation, for thousands of years, like an ancient forest in which no tree is old but the forest is. And to know how many thousands, and why that number is not greater, we must journey back to the ice, to an age when the sea itself had withdrawn from these shores and left the granite stranded far inland.

When the rocks wore no colour

TWENTY THOUSAND YEARS AGO THE world lay in the grip of the last great glaciation, and so much of its water was imprisoned in ice that the sea stood some 120 to 130 metres lower than it does today. Had you stood then where the Bicheno Blowhole now booms and sighs, you would have heard no sea at all, and you would have had to walk east, downhill, a long way across a cold and windswept plain before the water finally greeted you. To the north, Bass Strait was not a strait but a broad, grassy country, and people walked across it, for the ancestors of the Aboriginal people of Lutruwita had by then already lived upon this land for some 20,000 years, its first and most enduring witnesses.

It was a harsher country than now. Eastern Tasmania was several degrees colder, drier and windier, its north-east especially scoured by the gales, and sand blown off the exposed continental shelf piled into dunes far inland. Where forest now stands there was steppe, grass and scrub, and the granite of Bicheno was not shoreline at all but hill country, high and dry above that desolate plain. Some of it would have stood as bare grey tors, wearing the drab lichens of inland rock, but much of it, it seems likely, lay blanketed: in its own rotted crumbs of decomposed granite, in wind-blown sand, in thin soils bound by the roots of grass and heath. The great rounded boulders you now clamber over may well have been half-buried corestones upon a dry hillside, their curves concealed beneath grit and tussock, slumbering through the long winter of the world.

The orange existed. Somewhere out to the east, on whatever rocks then met the waves, there would have been a splash zone, and in it a belt of firedot lichens catching the sun, but it was not here, for here lay too far from the spray. It was not that the rock was too young, since it was already nearly 400 million years old. It was that its skin had not yet been offered to the sea.

Then the ice began to yield, and the sea returned, an inexorable tide of reclamation that at times came terribly fast. Across the flats of the old Bass Strait plain, researchers have calculated, the shore may have advanced more than 30 metres in a single year, enough to drown fifteen kilometres of country within one human lifetime. I can scarcely fathom the grief of those who witnessed it, who watched the places of their grandparents slip beneath the water, never to return. Somewhere between twelve and eight thousand years ago, the estimates differ, the sea closed over the land bridge, and Tasmania became an island. Along the east coast the waters climbed the shelf and pushed into the valleys, and as they reached the granite they stripped away the loose sand and soil and rotten rock, washed the hard old corestones clean, and left them standing in the surf like sentinels awaiting a long-promised dawn.

And as the sea ascended, the orange ascended with it. Picture it: a band of colour a few metres wide, travelling up the continental shelf ahead of the waves, millennium by millennium, an ancient procession keeping time with the tide. Each rock newly reached by spray was colonised, and each rock the sea finally swallowed was lost, for this lichen can bear a drenching but cannot live drowned. It has always been, in that sense, a refugee, forever moving uphill before the tide line, forever seeking the narrow, luminous margin between the land and the eternal sea.

The sea in Tasmania came to within about half a metre of its present height some 6,000 years ago, and has lingered close to it ever since. Only then could the orange settle at the height where you find it now, and so, on the rocks where you stand, the colour can be no more than six or seven thousand years old. It arrived at about the time the first cities were rising beside the rivers of Mesopotamia. The people of this coast, the Oyster Bay people, the paredarerme, had by then dwelt here for tens of thousands of years, and the orange, for all its ancient glow, is a newcomer in their Country, the latest thread in a tapestry far older than itself.

A conspiracy of sun, salt and wing

Taswegiuans will proudly state the orange is found nowhere else on Earth, and the truth is at once smaller and more marvellous than that. Firedot lichens live on every continent, Antarctica included. Upon the sunny rocky shores of Britain and Europe, lichenologists speak of an “orange belt” sitting just above a black band of other lichens at the top of the tide, and on Kangaroo Island in South Australia the same family paints the shoreline orange, red and yellow. The seam of granite running from Wilsons Promontory down through the Bass Strait islands carries its own orange too. What is rare is not the lichen. What is rare is the conspiracy of conditions that allows it to flourish here with such abandon, upon so magnificent a canvas, beneath so generous a sky.

Begin with the sun. Tasmania lies across the path of the westerly winds, and its western mountains wring the rain from them, so that by the time the air reaches the east coast it has grown drier and clearer, and the east is the milder, sunnier side of the island. Bicheno averages a little over six hours of bright sunshine a day and only around 670 millimetres of rain a year, and that rain is fickle, less dependable than in the west. On shaded shores elsewhere in the world, lichenologists have found, the orange thins and the belt fades to a leaden grey, but here, upon a coast that faces each morning across the open sea, the lichens manufacture their sunscreen in abundance, and that abundance is the colour, a radiant hymn to the very light that both feeds and threatens it.

Then there is the sea, which grants the lichen both its water and its limit. The orange dwells in the splash zone, beyond the reach of all but the wildest tides yet within the reach of the spray, and on a coast as open to the Tasman swell as Bicheno, that spray is flung far up the rocks, so that the band it nourishes is broad and brilliant. Heavy dew and the drift of salt mist complete the work, waking the lichen on mornings when no rain falls at all, a benediction delivered silently out of the grey dawn.

Then there are the birds. Lichens of this family are, as a rule, creatures of nutrient-rich surfaces, gathering beneath nesting cliffs and upon the rocks where birds congregate, because bird droppings are rich in nitrogen and phosphorus, the lichen’s very fertiliser. Granite on its own is a lean and acid rock with little to offer, but Bicheno is a bird town. Little penguins come ashore at dusk to their burrows above Redbill and Waubs beaches, silver gulls, crested terns and sooty oystercatchers breed on Governors Island across the Gulch, and shearwaters arrive each spring from the far north Pacific to nest on Diamond Island. Each of them carries the sea’s own nutrients up onto the rock, so that the granite is not the orange’s food but only its table, the feast delivered by the sea and by the birds, and it is the reach of the salt spray, enriched by those gifts, that draws the colour into its narrow band.

The srock matters too. A crust that grows a millimetre a year requires a surface that will hold still for centuries, and this hard, coarse granite, its crystals offering a thousand footholds, does not flake away beneath it, while its pale grey visage displays the colour as faithfully as a gallery wall displays a masterpiece, steadfast through every season the sea can summon.

And last there is the air. Lichens drink from the air as a sponge drinks from a puddle, and so they drink in whatever poisons it carries, and sulphur dioxide from coal smoke and smelters, falling as acid rain, erased lichens from whole landscapes of the industrial north, though some of the orange kin, hardier than most, endured where their grey neighbours perished. Tasmania sits upon the edge of the Southern Ocean, and at Kennaook/Cape Grim, on its far north-western tip, scientists sample what is often called the cleanest air on Earth. The east coast lies downwind of the island itself, but it has no smokestacks, and the lichens, in their quiet and luminous way, bear witness to the purity of every breath the ocean sends ashore.

The knife’s edge

FOR ALL ITS RADIANT BLAZE, the orange lives upon a knife’s edge. It needs the sea yet cannot bear to be drowned by it, it needs the sun yet must armour itself against it, and it needs to be soaked and then dried, soaked and then dried, over and over across the centuries, in a rhythm as old as the tide itself. Shift any of those things far enough, and fast enough, and the colour will fade from these rocks as surely as dusk fades from the evening sky.

The first is the sea itself, which is rising once more. Tasmania’s climate scientists now expect somewhere between 0.4 and 0.9 metres more of it by 2090, with storm tides riding higher upon it. Science is voicing its concerns for the firedots of the Bay of Fires for precisely this reason, observing that the lichen “certainly cops a lot of sea spray, but it cannot live submerged underwater,” and that it may have no chance to retreat to higher ground. On a tall headland the band might do what it did when the ice melted, and simply climb, but on the lower boulders around the Gulch there may be no higher ground, and the sea will close over the crown of the rock and the colour with it. The last time the orange climbed, it had thousands of years, and this time it has decades. Lichens have weathered slow change before, but what distinguishes our own age is its speed, the ceaseless acceleration of a world in a hurry.

The second is the warmth of the ocean. The waters off Tasmania’s east coast are warming at nearly four times the global average, driven in large part by an East Australian Current that thrusts its warm water ever further south. In 2015 and 2016 a marine heatwave lingered off this coast for 251 days, and in the summer of 2023 to 2024 another starved an estimated 629,000 shearwaters, which washed up dead upon beaches from Queensland to Tasmania, about three in every hundred short-tailed shearwaters alive. No one has yet measured what fewer birds would mean for the lichens of Bicheno, but if the colour is fed by the birds, and the birds are fed by the sea, then a starving sea will in time be written upon the rocks, a lament inscribed in fading orange.

The third is the rhythm of wet and dry. A dry lichen is astonishingly hardy and can endure rock heated to 60 degrees, but a wet one, awake and living, perishes when it climbs much past 35. In one experiment in a northern forest, lichens warmed by more than two degrees began to lose their algae and bleach, as coral bleaches, and it is usually the alga that cannot cope, says the lichenologist Simone Louwhoff, so that when it falters the whole partnership starves. Too much rain can harm as surely as too little, overwhelming the alga with stress, and climate models suggest the east coast may receive more of its rain in summer and autumn. What that rearrangement of wet and dry will mean for a creature tuned across the millennia to the old rhythm, nobody can yet say, and the uncertainty hangs over the shore like a sea mist that will not lift.

So what would it take for the orange to cease? Probably not any single thing, but several in concert: a sea rising faster than the lichen can climb onto rocks with no higher ground remaining, seabird colonies failing summer after summer, heatwaves cooking the crust while it is wet, air fouled by something we have not yet thought to build. None of these is certain, yet all of them are now possible, which was not true when our grandparents stood upon this shore and watched the morning set the granite alight.

The oldest thing you will touch today

GO DOWN TO THE ROCKS at Bicheno, early, when the sun has just cleared the sea, and the granite has begun to glow beneath its gaze. Step carefully, for the lichen is slippery when wet, and because a careless boot heel can scrape away a century in a single heedless moment. Then crouch, and lay your hand upon the orange.

Beneath your palm is a fungus and an alga, kin to a family that forsook the shade of the forests for bare rock a hundred million years ago. There is a crust that may have begun before your great-grandparents were born. There is a band of colour that rose out of the sea behind the melting ice and settled here some six thousand years ago, around the time humanity first began to build cities. And beneath it all lies a rock forged in fire close to 400 million years ago, before there was a flower or a bird or a blade of grass anywhere upon the Earth, a silent sentinel that has outlasted every epoch that sought to wear it down.

Our own stories upon this coast are brief and frayed beside it. We remember so little, and so briefly, while the rock remembers everything and says nothing, and the orange is its slow, bright handwriting, a chronicle inscribed in light upon the patient rock.

People come to Bicheno to gaze upon the sea, yet the thing most worth seeing lies at their feet: the oldest thing most of them will touch all year (maybe ever), wearing a living coat as fragile as it is beautiful.

We are only passing over it, as the ice once did and as the sea does now, and the most we can hope is to leave it as we found it, a quiet benediction against the ceaseless tides of time, burning, as it has burned through more than two million mornings, in the gold of the rising sun.

AM -

Sources

Geology

The lichen

Ice age and sea level

Climate, birds and place

Adam Martin
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