When I was young, and had newly learned that most stars were actually suns, I lay on my back one night staring up at a single star. I tried to imagine that this tiny prick of light was as large as the sun. Then I would shunt it backwards through space, pondering how long the imaginary “pipe” of space would be before it became star-sized again. As I looked down this tunnel a peculiar form of vertigo would overtake me. Even though I lay well-supported by solid earth, I grew dizzy with the vastness of space.
A different version of this psychic giddiness can be induced when contemplating geological time. For geology too shows us that solid earth is really an oxymoron. Take any place in southern or eastern Tasmania – say the Port Esperance area. Beneath your feet in such a place you’ll find evidence of just how fluid the earth can be. The rocks below carry tales of a break-up of monumental proportions: the bitter, long and literally earth-shattering bust-up that saw Pangaea torn apart some 200 million years ago. From our particular vantage point the agony of this break-up was largely kept below the surface. There were no volcanic eruptions; no glowing flows of molten material. Nevertheless the massive volume of dolerite which welled up below the surface – estimated at a staggering 15 000 cubic kilometres – would undoubtedly have been accompanied by a stark increase in earthquake activity. It would eventually leave its mark on nearly half the state. Today, from our Port Esperance vantage point, it is beneath our feet still. And it is also 1226 metres above us atop the pyramidal Adamsons Peak, as it is on so many of the mountains of Tasmania's eastern half. At Adamsons Pk, a mesa with a misleadingly volcano-like resistant cap, the constituent dolerite overlies the rocks that it long ago intruded upon: sedimentary rocks up to twice its age.
Those sedimentary rocks tell us that earlier still this area was a large marine gulf. Known as the Tasmania Basin, it collected sediment and run off from the now eroded uplands that pre-existed the present highlands. Up there, back then stood a whole unimagined, unexplored landscape; crisscrossed by rivers, crowded with unfamiliar life forms that doubtless never paused to consider themselves temporary. And now this landscape is known only from its reconstituted detritus.
Over more than 100 million years, taking in the Carboniferous, Permian and Triassic periods, this upland was brought down through patient cycles of erosion. In places the resulting sediment layers approach 1000m in thickness. Towards the end of this period, around 200 million years ago, the gulf dried out, became land-locked, and developed into a plain dotted with lakes. What was marine became freshwater. Fossils in these sediments have left a record of the life-forms that lived in this often cool time and place. These include shellfish, fish, reptiles, insects and ferns, but no flowering plants, birds or mammals, as these has not yet developed. While Pangaea was still intact, the relative stability that encouraged the development of the dinosaurs as well as these beds of sediment, was soon to end. That change came during the Jurassic period, and locally it was these vast sediment beds that would be violated, shattered and whelmed both over and under by the dolerite that accompanied the change.
It is curious to consider that geological changes are so ponderous by human chronology that most are out of our realm of experience. You might as well ask a bush fly to compare one cold snap with the next. Its life is so fleeting that the first cold snap is its last.
Yet geologists believe that the upheavals that accompanied Tasmania's part in Gondwana’s break-up – especially the massive upwelling of sub-surface dolerite – may have been so sudden as to be noticed by humans, had any existed at that time. Our proto-humans, living at sea-level in this region, may have found their surroundings elevated by as much as 400m over a period of years, perhaps even months. We can only conjecture what seismological and meteorological ructions would have accompanied such earthly turbulence and heat. And as to what our proto-humans would have made of it, assuming they were not overwhelmed by the sulphurous reek, we could as usefully turn to Dante or St John as to any science text.
When he opened the sixth seal, I looked, and there came a great earthquake; the sun became black as sackcloth, the full moon became like blood, and the stars of the sky fell to the earth as the fig tree drops its winter fruit when shaken by a gale. The sky vanished like a scroll rolling itself up, and every mountain and island was removed from its place. Then the kings of the earth and the magnates and the generals and the rich and the powerful, slave and free, hid in the caves and among the rocks of the mountains, calling on the mountains and rocks, "Fall on us and hide us from the face of the one seated on the throne."
In less apocalyptic times, a more neighbourly calling on the mountain we name Adamsons Peak requires you to traverse hundreds of millions of years. It is a long, mostly steep day's walk to the summit. But beyond the plateau's edge and its rind of sandstone, there is a respite, a near-level area of ground underlain by the sedimentary strata of the old Tasmania Basin. Novice walkers, exhausted by the steep initial climb, rejoice in the easier incline between the plateau's rim and the final cone of the peak. But every geology hides its secrets and, following a well-earned rest at the plateau’s edge, the walker enters a slough of boggy ground, its thigh-deep mud enough to bring back despond. It is only by travelling upward through both bog and time, and reaching again the solid dolerite of its higher ridges, that the walker is again on solid ground - at least during our current eye-blink in this geological age.
But what goes up must come down, in geology as in walking. Climate too has tides of which we are only dimly aware. The cold tides of climate, the ice ages, have bitten deep into the lands of this region, wearing down the vast bulk of material built up in the preceding ages. The jagged ridges and peaks of western and southern Tasmania might mimic volcanoes, but they are so-shaped for almost the opposite reason. Rather than being built up by forces acting from beneath, they have been ripped and torn by gravity and water - in both liquid and frozen form - until resistant remnants and watershed divides are all that remain at altitude.
If that wasn't enough, the white tide also wiped the highlands clean of much of its flora and fauna. The glacial ice became a chrysalis hundreds of metres thick, encasing for millennia many of the old life forms of the island. When the land finally emerged from its icy carapace, a metamorphosis occurred. A new creation was revealed, with completely new species, genuses and even orders emerging to take the place of those that had been overcome by ice.
At the same time Pangaea, and then its child Gondwana, continued to break apart. Finally around 45 million years ago Tasmania farewelled Antarctica. We slowly moved towards the middle latitudes, warming and drying, while Antarctica stayed south, its flora freezing and dying out by around 17 million years ago. For Australia the dramatic changes in climate brought new species, genuses and orders to replace many of the Gondwanan life forms. But not everywhere. The highlands of this island were some of the last places to resist the invasion of one of these newcomers – the eucalypt. The archetypal Australian tree is actually a botanical johnny-come-lately, having only arrived some 25 million years ago. Its phenomenal success, due in part to its ability to cope with drought and fire, is nowhere better illustrated than in the tall old growth forests of southern Tasmania. Yet their success is not absolute. Inland of Port Esperance it is possible to climb out of eucalypt forest and into the woodlands of old Gondwana, where myrtle, tree fern, celery-top and King Billy pine predominate.
If these vast sweeps of geological time and the rising and falling tides of ice and life-forms blur your mind, then scale down the time frame and consider what’s happened at Lake Eyre only recently. In early 2004 Coopers Creek and the Thompson, Barcoo and Diamantina Rivers were all in flow. Their waters journeyed hundreds of kilometres from the rain-soaked interior of Queensland, moving at a steady walking pace. After tireless months they reached and then slowly filled Lake Eyre to its highest level in years. In parts the water was over 1.5m deep, even encouraging the (very) occasional sailors of the Lake Eyre Yacht Club to wet their keels.
But with the in-filling came not only a flood of water, but also a flush of fauna and flora that brought people from around the world just to witness it. For months the lake was alive with invertebrates, fish, amphibians, reptiles, birds and mammals. Plants and seeds that looked dead for decades sprouted, flowered, seeded and regenerated again, in turn bringing birds, insects and all manner of other living things. Mobs of kangaroos; platoons of pelicans and murders of crows travelled hundreds, even thousands of miles to join in the feast.
With the flood came movements of sediment on a massive scale as bare earth was scoured by the rush of floodwaters. On the lake’s new shorelines short-term beaches and dunes even formed as wind and wave did their work. The dunes in turn were colonised by plants and burrowed in by animals. For perhaps three years, depending on follow-up rains, these changes will transform what Charmian Clift once called an "incurable acid-wound" into an oasis of sorts. Alter the time frame by several factors, and it’s analogous to sea level change and glaciation. Just as the micro time-scale event at Lake Eyre brought with it major movements of plants, animals and earth materials; so the macro time-scale events cause enormous environmental shifts across continents, nations and islands like ours.
Whichever time-scale we use, as we come to the present and the future, we must consider one more compelling environmental factor. To all of this layered chronology, we must add human history.
In his 1977 book A Time of Gifts, Patrick Leigh Fermor recalls gazing out over Slovakia before World War 2. He reflects on the human upheavals that have characterised central European history.
The shift of mountains and plains and rivers and the evidence of enormous movements of races gave me the feeling of travelling across a relief map where the initiative lay wholly with the mineral world. It evicted with drought and ice, beckoned with water and grazing, decoyed with mirages and tilted and shifted populations . . . steering languages, breaking them up into tribes and dialects, assembling and confronting kingdoms, grouping civilizations, channelling beliefs, guiding armies and blocking the way to philosophies and styles of art and finally giving them a relenting shove through the steeper passes.
We know little of the tilts and shifts of human populations which occurred here in southern Tasmania before European take-over. We know that caves less than a half-day’s walk from Port Esperance were used by Tasmanian Aboriginals during the last ice age. And we suspect that no humans anywhere else on earth lived this far south at that time. We also know that these same people had a profound effect on the type and occurrence of flora and fauna through their deliberate use of fire. Yet we know so little detail of their history here; of their thoughts and beliefs; their loves and losses, even though theirs is a far longer history than that of Europe. Leaving aside geological vertigo, even the number of generations of Aboriginals dwelling here is dizzying. Perhaps 1500 generations had come and gone, and Bass Strait had closed, opened and closed again, before the English invaded a mere 7 generations ago.
And now what? Listen to a few lines from Pete Hay’s poem 1842: William Lanney at the River.
It is not mine to know -
not mine to know why the last free people,
William Lanney's family,
chose a social death
to the solitary sorrow
of the ghost-fled scrub.
The tracks of the people blur for want of feet,
the ghosts retreat
to still places
in the distant heart of trees,
in the mat of sunken scrubroot.
And all around,
relentless
clamping silence fans to the sea.
The boy from the Black Bull Scrub
grows strong, childless, kindly,
well-fashioned to bear a people's weight.
He dies in the Dog & Partridge;
the local hounds of science
finesse the devil
for the chance to tear him apart.
All make the trick:
Bacon's children gouge and chop
and deem themselves noble
in colonial Hobart -
but I fly to the Black Bull Scrub,
lose myself there,
lean to the salt-laced wind,
wishing, for one omniscient instant,
to touch the lonely edge
of a family
stepped forth
from the hauntless bush.
All here are gone
Gone from the sun
With the wind
As it flows to the east.
Who were the land
Its sap and its kind
Are lost;
In its silence the land is lost.
Yet here we are. We can be no-one else and, for the moment, be nowhere else but here at the sharp end of the 7th generation of Europeans in Australia. We’re part of an Earth generation that has overcome our vertigo and landed humans on one dot in space, and is looking further afield. We’re part of a generation that has renounced its need to attribute earth movements to God, although we may question whether putting ourselves in the deity’s place is such an advance.
Some come to Tasmania from places where human greed and hubris have left their ugly, inescapable bruises on the landscape. Others call Tasmania home. But whatever our origins we can see for ourselves the disproportionate tilts and shifts that result from the exertion of human will, even here in our heart-shaped island. From our nominal vantage point of Port Esperance we cannot help but see the vastly accelerated changes at the species, genus, order and even landscape levels.
And seeing these changes, even in this literal backwater, I pause to consider how we can find ways of keeping this place intact for coming generations. Tasmania has had too long a journey, come through too much geological upheaval, to meet some ugly end at the hands of humans. I seek comfort in remembering that Esperance means hope.
Peter Grant, October 2004
[Published in Island magazine #102, Spring 2005. An earlier form of this essay was prepared for a conference held at Port Esperance near Dover. The geological advice of Mike Pemberton is gratefully acknowledged.]
