Time, gentlemen, please
From Griffith REVIEW Edition 12: Hot Air
© Copyright Griffith University & the author.
Written by George Seddon (dec.)
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George Seddon's biography and other articles by this writer
Much of the geology I once learned is long forgotten, but what remains, indelibly, is an awareness of time, geological time. Much of my work was in the late Devonian, more than three hundred million years ago. That did not long seem strange: it was my familiar working time, full of detailed subdivisions (Frasnian, Famennian, etc.) which were the hours, minutes and seconds of that geological time clock.
Political time, with three– or four-year elections, is fleeting; anthropoid time, with about a twenty-five year turnover, is equally transient. Both are ephemeral events like the life of a butterfly, although that is not to deny that the lifespan of the butterfly is all-important to the butterfly, as it is to the anthropoids and other ephemerids.
One of the discrepancies in time scales that irks me lies in weather reports. Every day we read the expected daily maxima and minima, how these relate to the average for that time of the year, and the rainfall against the monthly and annual average. The weatherman is doing his job and what happens next is not his fault: he is forecasting – making educated guesses, in an uncertain environment. Many people, however, more or less expect the average, or near to it, and feel aggrieved if they don't get it. "The forecast was wrong again," they say. But a forecast can't be wrong, it is a forecast. All that can happen is that it not be fulfilled.
Accurate rainfall and temperature records, on which probabilities are established, have only been kept in Australia, or anywhere else for that matter, for a century, give or take a few decades either way, so the "averages" have very limited substance. Even in historic time, change has been the norm. Think of the Danes in Greenland in the eleventh century or thereabouts, successfully farming land that has since been blanketed in "permanent" ice and snow. In the early Middle Ages, Merry England was indeed merry, with wine grapes growing in the Thames Valley – yet by the seventeenth century, sometimes known as the Little Ice Age, the Thames was frozen solid in the winters and bonfires were lit on its surface to roast Manningtree oxen (whatever they are or were). There is a great account of this in Virginia Woolf's Orlando.
I remember being impressed, on my first visit to Copenhagen years ago, by the very steep pitch on the roofs of the older buildings that went back to that period, roofs clearly designed for efficient snow shedding, since the weight of accumulated snow could break the roofs of the day. Now Copenhagen, like all big Western cities, is wrapped in its own heat blanket, but even without it there is no need for snow-shedding roof lines.
In the same century, the Dutch first came to Rottnest, off the coast of south-western Western Australia, and their reports suggest that the island was much better timbered and much greener than it is today, implying a rainfall of about 1,200 millimetres rather than that of today, which is under 800 millimetres. Much of it is now an arid steppe, although climate change is not alone responsible for that. All these changes have been within historic time, which is still little more than the blink of an eye to a geologist.
IN MY MOST RECENT BOOK, The Old Country: Australian landscapes, plants and people (Cambridge University Press, 2005), I have written about time and space (our space or place). For my Australian-born mother, the "Old Country" was Britain, as it was for most of her generation, although she had never set foot on its sacred soil. Neither had she ever been "Home", although she first left home (in central Queensland) at the age of twenty-three to be married and returned often. But Australia is "Home" and we should start behaving like it is. The latitude of Fremantle, where I live, is that of Marrakesh on the edge of the Sahara. The latitude of Hobart is that of Rome, although Rome tends to be colder in winter and hotter in summer. Their similarity in climate was remarked upon by several early English visitors, but if I mention that today, I am met with disbelief. Occasionally someone looks it up, and reports back with amazement: "My God, you're right". Australians no longer know their geography.
For my generation, Australia is also the old country. Many of our landscapes are immensely old. Last year I spent some time in Lazio, the countryside around Rome, and was reminded yet again how new is that landscape. We had lunch beside Lake Albano, a volcanic crater that erupted in mid-Pleistocene – yesterday to a geologist. It pushed up from the sea floor. Rome and all the countryside around it was under water two million years ago. The sharp contrast between an old, rich culture and a brand-new landscape, hardly yet dry from the sea, is not surprising. The fertility of Lazio underwrote and underwrites that cultural growth.
Although most Australian landscapes have undergone countless cycles of weathering, most of them have been high and dry for hundreds of millions of years. And Australia has not experienced the cataclysms of mountain building that resulted in the Rockies and the Sierras that transformed the "New World" and built the Alps in the "Old World". We don't do mountains here. Our "alps" are the tilted and eroded edge of a minor plateau near the eastern margin of the continent. Everything to the west of the Great Divide – hardly "Great" – is part of western Australia, a huge landmass that includes western New South Wales, western Queensland, all of South Australia and, of course, Western Australia. We would have done far better to follow the example of the Americas, both North and South, by having our continental divide about four times higher, running through Kalgoorlie. It wouldn't have made much difference to western Australia, but it would have made a huge difference to the east.
Massive glaciations scoured the northern half of both the northern continents, North America and Eurasia, in the Ice Age, wiping the slate clean, a new beginning for plants and man. Our last comparable ice age was in the Permian, not one million but more than 200 million years ago, when most of the western third of the continent was scoured and scored, the striations sometimes still to be seen in the ancient granites and gneisses of the Darling Plateau near sunny Perth.
Geology is a continuum so, like every other landmass, Australia has rocks of all ages from the Archaeozoic – almost the beginning of earth time – to the present, including comparatively recent volcanic activity in Victoria and the drowning of a substantial fringe of coastal land when the seas rose with the melting of Pleistocene ice in the northern hemisphere some 10,000 years ago. There are old rocks in every continent, but the Precambrian in Australia is exposed over a vast area and well studied, largely because of its mineral riches.
What is more important than the age of the rocks from a human point of view is the age of the soils, and even in geologically younger eastern Australia, the soils are mostly old and leached of nutrients.
As a political entity, Australia is, by contrast, a very young country. A few years ago, there was a rhetoric to go with it: we have the virility of the young, unlike the effete Europeans (other than, of course, the British, our immediate antecedents, whose virility is eternal). Now the tenses change. They change in the United States, whose youth is/was "one of its hoariest traditions", according to Oscar Wilde. They change in Australia, and in Britain. Old Father Thames may keep rolling along (into the mighty sea) but the North Sea is a drop in the ocean and young Father T hasn't been rolling into it for long, either. Some Australian rivers have been following much the same course for much longer, but we do not have enough words for degrees of "old". "Ancient" belongs to B-grade fiction. "Immemorial" sounds promising, but since nearly all of geological history is beyond the reach of human memory (is immemorial) it is of little help in discriminating degrees of "old".
THERE IS A ROUGH DIRT TRACK LEADING SOUTH FROM THE ROAD from Port Hedland to Marble Bar in north-western Australia that leads to an old mine site. Nearby, there are several outcrops of fossil stromatolites and they are up to 3.5 billion years old, among the oldest known evidence of living organisms. The stromatolites are in the Warrawoona Group, which are mostly volcanic lavas, but with some layers of sediment accumulated in shallow seas. Beneath these rocks, there is an angular unconformity or ancient erosion surface (a page missing in the local journal of events); the eroded rocks have been dated to 3.515 billion years. For erosion to take place, they had to be at the earth's surface. This is the first reliably dated evidence of a stable crust. The world was beginning to assume its present form, so we are watching the curtain go up. It must have gone up elsewhere, but this is the first record, first by more than half a billion years. Now that's old.
What was it like? Steamy. Volcanoes erupting, cooling lava, shallow seas, igneous rocks, mostly granitic, heaving away like hot thick porridge down below. A reducing atmosphere, mostly nitrogen and carbon dioxide, with traces only of oxygen. Yet there was life, including the cyanobacteria quietly building their layer-cake mushrooms of alternating sediment and organic films that we now call stromatolites.
They kept at it. Moving south and a billion years later, the stromatolites were abundant in what is now the Hamersley Basin. At some point in time they became photosynthetic, able to harness the energy of the sun – for all of us, for this was a step of far greater significance for our species than the landing on the moon. Most of our energy, including all the fossil fuels (rocket fuels included), our wood fires, our food, are directly or indirectly dependent on it.
But that is only part of the story. Oxygen was a toxic waste product for cyanobacteria, and they excreted it by combining it with the ferrous oxide dissolved in seawater, precipitated as ferric oxide. This is abundant in the banded iron formations, more than a kilometre thick, mined at Newman, Tom Price and Shay Gap, and exported in massive quantities. You may not be enthusiastic about stromatolites and the cyanobacteria, but given that they paid for the nation's Nissan Patrols and Miele electric ovens, television sets and holidays in Provence, Australians might at the very least spare them a kind thought in their prayers. Nearly one-third of Australia's export income comes from the sale of minerals from Western Australia, and those little micro-organisms were working away quietly on behalf of this export industry some 2.5 billion years ago – not, of course, only in Western Australia, but they are most spectacularly exposed in the Hamersleys.
Working for the future balance of trade was not their only positive contribution; as they locked up most of the ferrous ions in seawater, they released oxygen to the atmosphere and this began the next major phase of global evolution. An oxygenated atmosphere allowed the appearance of new kinds of organisms. Simple cells somehow acquired a nucleus, a handy little command post and communications centre. Another major step was the appearance of sexual reproduction requiring genetic recombination, not as efficient as simple division, but definitely more fun, and very useful in times of rapid environmental change, adding a second evolutionary mode to random mutation.
Then, towards the end of the Precambrian, soft-bodied, multicellular creatures made their debut. Once again, they were first found and are best displayed in Australia, but this time in the Flinders Range, in the Pound Quartzite at Wilpena. After that, the umpire blew the whistle, and the race was on: trilobites, primitive fish, early land animals and plants, the dinosaurs, the mammals, the mammoths, us – all this in a mere 500 million years.
When I was young, I read The Timeless Land by Eleanor Dark. Australia was the place where time stood still. But she got it wrong. In a sense, Australia was the place where the clock started ticking. Nor did it stand still during the up to 50,000 years of Aboriginal occupation, a time that saw dramatic changes in the climate, the flora and fauna, and in the boundaries of a continent that embraced New Guinea and Tasmania. The stories of Aboriginal adaptation to these changes are being recovered by archaeologists and increasingly by anthropologists who have begun to take seriously the Aboriginal explanations of their past, which tell of rising sea levels, parts of the land becoming offshore islands, volcanic eruptions and of large animals that once were hunted and then became extinct. "These explanations can be found in the rock engravings, in the paintings, in the songlines and in the Dreaming," according to Keith McConnochie in Departures: How Australia reinvents itself (MUP, 2002).
Most of the Pilbara was better watered 60,000 years ago than it is today, and remained so to about 25,000BP, but the world then began to cool as it moved into the last ice age. The Pilbara and the Western Desert became colder, windier and much more arid, and by 18,000BP they were emptied of people except along the coastal fringes (which extended further west than they do today) and in a few isolated refuges like the Hamersley, Petermann and MacDonnell Ranges, where water could still be found in deep ravines. For as long as 10,000 years, small communities survived in such refuges in the interior without any possibility of contact with one another. Only in the Holocene period did the climate begin to ameliorate, and by the time of European arrival on the continental fringes, the interior had all been repopulated, although thinly. "The view of Australian Aboriginal culture as an unchanging timeless culture in an unchanging timeless land is clearly an untenable representation," as McConnochie wrote. Time, gentlemen, please, and ladies, too.