The Cadell Fault and the formation of the Barmah-Millewa forests
At some time in the last 60,000 years a comparatively minor bump in the earth's crust had a major effect on the Murray River and a couple of associated streams. It is claimed to be one of the world's most spectacular examples of seismic activity altering the course of a river.
Scientists are still working to explain exactly what happened and when but recent research suggests that several large earthquakes pushed up the land between where Echuca-Moama and Deniliquin now stand and dammed what was then a very mighty Murray.
Until perhaps 45,000 years ago the Murray flowed westward through the area where Mathoura now stands.
It is thought by some scientists that the uplifting of what we call the Cadell Tilt had begun perhaps fifteen to twenty thousand years before this. The river eventually found a way over the edge of this first uplift and found its old bed but when a new block was suddenly thrust up the river had nowhere to go.
The weir held back both the Murray and the Goulburn rivers, initially flooding a huge area.
Eventually the Murray turned north, most of its water flowing through what we now call the Edward while still filling the northern lake. The Goulburn probably joined the Campaspe at this time. Eventually it formed Lake Kanyapella which covered an area from south of Moira to the other side of where Echuca now stands. In big floods this depression still fills.
The Murray built silt jetties into the northern lake which defined its later course through “the narrows” or Barmah Choke.
The landscape was then quite different to what we see today. There were no great forests.
In fact there were no river red gum trees at all. Pollen from soil tests show that red gums invaded the area only about 6,000 years ago. At around this time there is also evidence of tree ferns growing along the Murray. The river banks were mostly open woodland and grassy plains although the higher ground west of the uplift was arid.
Until the end of the last ice age, about 20,000 years ago, glaciers covered the ranges near Mt Kosciuszko, contributing a steady stream of meltwater which fed the Murray for most of the year.
During one dry period sand from the floor of the northern lake was blown to form the long sand dune along which Picnic Point road travels. Lake Kanyapella also dried. The dune system known as the Barmah sandhills resulted.
Once wet times returned the lake refilled from an overflow even though most of the Murray’s water by then flowed north in the Edward river.
Trees would not have survived what were probably quite long inundations but Moira grass, a type of couch, flourished.
Then in quite recent times, well after the arrival of the aboriginal people, the Murray established a new course southwards, joining the Goulburn which by then flowed through the present site of Echuca-Moama. Lake Kanyapella had by then either drained or silted up. Part of the depression which was the former Kanyapella lake bed is visible to the south of the Cobb Highway between the Barnes railway crossing and the Heartland Speedway near Moama.
Local aboriginal legend says that their ancestors helped the river break through by digging through a sandhill during a massive flood event.
The 1870 flood was the largest ever recorded at Echuca but at that time aborigines spoke of even bigger ones in the past.
Scientific testing by Dr Tim Stone of the section of river bank between Picnic Point near Mathoura and the Victorian town of Barmah (known as The Narrows or the Barmah Choke) have shown that the channel is only about 550 years old. The river here has straight-sided banks whereas older sections of river show the normal sloping sides of a mature stream.
Notes on the Barmah-Millewa forests
The Barmah-Millewa group of river red gum (Eucalyptus camaldulensis) forests grow on both sides of the Murray river downstream from Tocumwal, extending almost to Echuca. They are often wrongly described as “iconic”. They are also wrongly called “ancient”.
When the first white men came here they saw a very different landscape to that of today.
There were practically no forests when people like explorer Charles Sturt and the squatters Edward Curr and Henry Sayer Lewes arrived.
Lewes, a well-educated Englishman, described the river flood plain now occupied by the Moira forest when he founded Moira Run in 1842 as “mostly clear swamp where afterwards it became covered in impenetrable reed beds.” Report of inquiry into the state of public lands and the operation of the land laws. Instituted 8TH January, 1883. Journal of the Legislative Council, 1883, Vol. 34, pt. 1
An 1848 map known as Mr Boyd’s Map of the Edward River Country (in the NSW Government archives) shows it as “Gum Swamp”
The impenetrable reed beds had caused problems further upstream for Charles Sturt in 1838.
The man who named the Murray during his expedition down the Murrumbidgee in 1830 wanted to know if it was the same river as that named the Hume by Hamilton Hume and William Hovell when they crossed it in 1824 near where Albury now stands.
He also had some cattle he wanted to sell in the infant settlement of Adelaide. So he drove his stock to the Albury area and began following the Hume downstream.
After leaving the hill country he remarked that the country along the river was mostly grassy plains and reedy swamps, with trees mainly in the distance.
By the time he reached the place where the Edward river flows out of the Murray, near the centre of today's Millewa forest, the reeds had become thicker.
He met aborigines at that point who told him with sign language that he would get no further because the ground ahead of him was flooded. One of his stockmen, sent out as a scout, confirmed that they would not get their drays through the reeds, swamps and creeks. Sturt crossed the river into today’s Victoria.
He found similar conditions there. The only way through the tall rushes was by following tracks made by the aborigines. It took him two days to skirt what he called a “vast marsh” (now the Barmah forest) and meet up with the Hume again, about where the township of Barmah now stands. Course of the Hume River, from the Hilly Districts to the Junction of the Morumbidgee. By Captain Charles Sturt. Journal of the Royal Geographical Society of London, Volume 35. Pp 141-144
As he travelled towards present day Echuca-Moama Sturt complained of a lack of firewood which meant no campfire and no cooked dinner for he and his men.
In 1841 the squatter Edward Curr, who had taken up Tongala Run on the lower Goulburn river visited the Murray near Barmah Lake.
Climbing a large solitary gum tree on the river bank near the junction of the Broken Creek he observed “a sea of reeds, of several miles in extent, as far in fact as the eye could reach”.Curr, Edward M: Recollections of Squatting in Victoria, first published 1883, reprinted by Campaspe Shire 2001, page 168.
Curr’s book explains the lack of trees.
He was one of the first people to write about “firestick farming” and he well understood that the aborigines used it very deliberately to encourage grassy plains. River red gum is very fire-sensitive, particularly when young. Regular burning kept what is in fact a very invasive and opportunistic species under control.
There were no forests because the aborigines did not allow them to grow.
The advent of white settlers brought a swift end to thousands of years of tribal aboriginal culture.
Without the regular burning, but still subject to almost annual flooding by the river, the red gums flourished. In dryer years they were able to invade some of the swamp lands and, once established, helped to drain them by transpiration.
This view is supported in Julian di Stefano’s River red gum (Eucalyptus camaldulensis): a review of ecosystem processes, seedling regeneration and silvicultural practice (2001).
He wrote: “The cessation of burning by Aboriginal groups facilitated increased red gum regeneration during the last part of the nineteenth century.”
He also quoted Chesterfield (1986) as saying: “reduced spring flooding has resulted in the invasion of red gums into areas previously too wet for them to survive.”
Note that this does not mean a complete absence of river red gums during aboriginal times. Curr described large old trees along the watercourses, as did Sturt. That’s their natural growth pattern. But there is no historical evidence of widespread and dense forest as we know it today.
The arrival of the railway at Echuca in 1864 triggered an interest in harvesting the forests so that by the time it was extended to Deniliquin in 1876 these virgin forests were supplying huge quantities of railway sleepers and also mining props for the underground leads being developed at Bendigo and other goldfields.
The durability of the timber was a major factor in its growing importance. It is resistant to rotting under ground or water and to termites. It makes ideal railway sleepers.
The growth of the new settlements brought a demand for building materials which was also satisfied by the rapidly growing trees.
The growth habit of the timber caused a reporter from the Deniliquin Pastoral Times to marvel in 1889: “It grows, apparently, as fast as it is cut, in fact the cutting and recovering of timber from these State forests under proper supervision, seems to make that which remains grow more luxuriantly than ever.” Pastoral TimesMay 18 1889
The timber built wharves and bridges. Red gum blocks from the Barmah-Millewa forests once paved the streets of Melbourne.
Sawmills flourished and little settlements grew into timber towns.
In the 1870s a Scottish entrepreneur, Robert “Red Gum” Barbour, had six or seven mills along the mid-Murray and a similar number of paddle steamers to haul logs to them and tow barges laden with the milled timber to the Echuca railhead.
Under the Robinson Land Act of 1861, he was able to buy river frontage along the Murray. Under the act he was required to clear the land, to which task he applied himself with great enthusiasm, clear-felling the forest until a neighbouring settler, Henry Ricketson, warned the NSW government that there would soon be no forest left if he was not controlled.
It was probably the first environmental battle fought in Australia and it was led by a squatter!
Today there is barely a trace left of Barbour’s wholesale plunder. The forest indeed grew back “more luxuriantly than ever.” Deniliquin Pastoral Times, various editions.
It was the beginning of real regulation of the timber industry along the Murray.
Careful stewardship by Forests NSW has ensured sustainability for well over a century.
It is their foresters who decide, under strict guidelines, which trees are cut down.
Known habitat trees are marked with a small, permanent plaque and protected from harvesting. Nest sites of vulnerable species are given a buffer zone. The wetlands, particularly those recognised under the Ramsar treaty, are similarly protected. They are not logged or grazed.
The recent sighting of nesting brolgas within the Millewa forest attests to the success of the management. They are the first breeding brolgas in about fifty years to nest there.
Birds and animals do not choose nesting sites because they like the scenery. They choose them because instinct tells them that current conditions will provide enough food on which to raise a family.
Currently the forests face a huge challenge but it has nothing to do with either the timber industry or the administration.
It is 16 years since the trees last had a decent drink. In 1993 one of the highest floods ever recorded covered the entire forest floor. The upsteam dams were filled to overflowing. It was water nobody wanted at the time. But the trees loved it. And more young seedlings sprang up.
Since then there has been one minor flood event and several environmental releases which were mainly used to water the wetlands, not the trees.
Subsequent droughts and the demand for irrigation water to grow food for our expanding population has meant that the storage reservoirs have not completely filled since that epic flood.
Putting the trees into a national park is not going to save them.
In fact Yanga National Park, Bob Carr’s farewell gift to the state of NSW, is one of the worst affected areas of river red gums in the state. Possibly 90 per cent of the trees are either severely stressed, terminally stressed or already dead. Yet right up until the day Carr signed over $30 million of taxpayers’ money to buy the famous old private property, its forest was supplying sustainably harvested timber to a large sawmill.
Carr presented it to the media as a fine example of riverine forest but he did not tell the good people of the press that it had been selectively harvested for years. Yet it was the careful management of the felling program that produced such an attractive forest.
Of course Carr’s purchase did not create the drought. But it sure didn’t save the trees from a fate worse than death by falling either.
The real problem is that river red gums have a prodigious appetite for water but the climatic region in which these trees are growing borders on arid. The average annual rainfall, while sufficient to keep the scattered box trees of the dry plains alive, is never enough to support so many trees so close together which are so reliant on water. They survive by sending roots down to the water table.
Protracted droughts lower the water table faster than the trees can grow roots. But trees transpire the water they drink. The more trees, the quicker the water table drops.
There are now more river red gums along the mid-Murray than at any previous time. Not just in the last century, or since white settlement or in recorded history — ever.
They have literally grown faster than we were cutting them down and in doing so have created a huge problem for themselves.
The only way they can get enough to drink is from floods which recharge the water table.
Floods big enough to cover the entire forest represent an enormous amount of water and occur, usually unpredicted, about every 20 years.
For a number of reasons it is not helpful to flood the forest in summer. But summer is the ideal time from a logistical point of view because these days the river is already full then, taking stored irrigation water down the valley, so it requires comparatively less “extra” flow to create an overbank flood. But in the winter, the best time for the trees — and the breeding birds — to benefit, the river is usually low while the dams upstream are hopefully refilling.
Short of taking the entire contents of one of the major storage dams every five years (as calculated and recommended by the Victorian Environment Assessment Council in its preliminary report on the Victorian red gum forests assessment) and pouring it into the forests, the only sane solution is to cut down many more trees, giving those that remain better access to the precious resource.
The solution proposed by ex-Premier Rees, prodded by ex-Premier Carr to lock up the trees in a new national park will not come even close to “saving” the dying red gums.
If we do not get a major flood very soon, his new conservation reserve will be full of dead “iconic” trees and abandoned “iconic” nesting sites and no amount of political posturing will change that.
Researched and written by David Joss,
Mathoura NSW
Phone (03) 5884 3510
Professor Vanclay believes there are several major forestry issues currently facing the planet.
"Some symptoms are the MIS (managed investment scheme) plantations and the failure of plantation foresty companies; the debate about plantations versus water use; about using food crops for biofuels (yes, that's forestry, because one productive option is to grow eucalypts for energy); about carbon sequestration in tree plantations; about national parks versus harvesting of native forest; and about the management of the red gum forests (in the media recently)," he said.
"But these are all symptoms of the real problem. The underlying issue is how society understands natural ecosystems and understands the whole-of-system impacts of our resource use.
"Wood is the most environmentally friendly building material, and natural regeneration is the most environmentally friendly production system, but many people object to native forest harvesting and happily use inferior imports or non-renewable substitutes, because they have not fully considered the whole-of-system consequences.
"One of the challenges of forestry is to get people to see the big picture: we rejoice in babies and dismiss the messy childbirth, we admire the Sydney Opera House and overlook the long and messy construction period, but few other than foresters can see through the harvest residue to see the new opportunity for forest regrowth. That's where the big challenge lies."
