Download The Plutonic Waters of the Great Artesian Basin

The Plutonic Waters of the Great Artesian Basin
December 2000
By Emeritus Professor Lance Endersbee AO FTSE
Synopsis:
In two previous papers in Focus on the Great Artesian Basin (see references) I put forward my view
that the present official concept of recharging of the Basin from surface waters was incorrect. At the
time I was not certain as to the actual origin of the waters, only that recharging from surface waters
was a physical impossibility. My continuing studies set me on a quest for the source of the waters.
It was evident (to me anyway) that the sedimentary rocks of the artesian basin should have been dry
before there was any drilling of boreholes. Examination of records from 1888 showed that the
sediments were mostly dry when the first bores were drilled. Water was found in the bedrock below
the strata, and often at high pressures. I concluded that the water had subsequently entered the
shallower strata from these deeper boreholes, by the simple process of hydraulic jacking from the
high-pressure waters of the deeper bores.
The deeper underground source meant that the waters were of plutonic origin. The water is of similar
origin to the waters that explode as steam from volcanoes, and gush from the deep ocean vents. The
eastern boundary of the Basin merges with a wide zone of recent vulcanism extending from Cape
York to Tasmania, and which has been active in the last 40 million years, most recently at Mt.
Gambier only 5000 years ago. The chemical composition of the waters, the temperatures and the
association with natural gas all confirm a plutonic source. The huge volume of water already taken
from the Basin, say 100 times Sydney Harbour, is also consistent with a volcanic source and certainly
not slow seepage through the strata. The waters probably accumulated during this period of
vulcanism, and may represent an accumulation over tens of millions of years. I believe that the
present usage of the water from the Basin greatly exceeds any potential recharge from these deep
sources.
I have also concluded that these deep plutonic waters also form a water drive for all of the resources
of oil and natural gas in this same area, and the nearby resources in the Otway and Gippsland
Basins.
As the sustainability of both the water resources and the petroleum resources depends on the drive of
the plutonic waters, I think it is critically important to ensure that all these resources be understood
and managed as parts of an integrated system of natural resources. Thus the continuing waste of
artesian waters is highly damaging to the potential recovery of oil and gas as well as limiting any
future recovery of water. I think this is a matter of critical national importance.
A wonderful aspect of my studies has been the discovery of the writings of J. W. Gregory, FRS, who
was Professor of Geology at the University of Melbourne from 1899 to 1904. In 1901-02 he took a
party of students into the area around Lake Eyre, and studied the flowing bores of Central Australia.
Gregory, who was an outstanding scientist with wide experience in geology, and who had studied the
geothermal waters and volcanic features of the Great Rift Valley in Kenya, stated quite firmly that the
waters were plutonic. He was quite right, and that was 100 years ago.
Here we are 100 years later, and Australian scientists, the several governments involved, and the oil
and gas industry operating in this region, have not yet comprehended the simple truth that was stated
so clearly and positively by Gregory so long ago. The paper discusses how the present sad situation
came to pass.
THE GREAT ARTESIAN BASIN
The Great Artesian Basin spans four states and covers one fifth of Australia. The rocks are a normally
consolidated sedimentary series of Jurassic and Cretaceous age. Down-warping of the crust of the
earth has created a saucer shaped basin, with a maximum thickness of sediments of about 2000
metres.
Figure 1: Under the Constitution, water is a
Figure 2: Although the total flow has been
responsibility of state governments. The
management of the Basin is the responsibility of declining since 1917, it has not been taken very
seriously because of the firm belief in the
three states , ie Queensland, NSW and SA, and
rechargeability from surface waters in the 'intake
the Northern Territory. It is my view that this
division of responsibilities for the management of areas'. Possibly 95 percent of the total outflow
this important national resource is one of the
over this period has been wasted .
causes of the serious problem now facing the
nation.
Drilling of bores into the Basin began in 1886. By the end of the century, in 1899, there were 524
wells, of which 505 were productive. The yield at the end of 1899 was 1000 megalitres per day, a
remarkably large flow of water. But by 1899 there was already concern about the declining flow from
most bores.
The total discharge from the Basin reached a maximum in 1917 and has been declining ever since,
despite an increasing number of bores.
MANAGEMENT OF THE BASIN
The state representatives, together with an Australian Government representative, meet as a
Technical Committee. There is also a users group called The Great Artesian Basin Consultative
Council. Mr. John Seccombe, who has a property near Longreach, is Chairman.
The 'official' version of the operation of the Basin is shown in the website of the Queensland
Government, from which the following diagram and text are taken. (
http://www.dnr.qld.gov.au/water/artesian_basin/flow.html )
WHY AN ARTESIAN BORE FLOWS
"Artesian" water is underground water confined and pressurised within a porous
and permeable unit, an aquifer. The aquifers of the Great Artesian Basin consist
of permeable sandstones. These aquifers are recharged by rainfall infiltrating
into the uplifted and exposed sandstones on the edge of the basin. Recharge
waters slowly move down through the sandstone, filling the aquifer to the level of
the intake area. As the aquifer is confined by an overlying impermeable unit, the
water becomes pressurised. When a bore is drilled into the aquifer, the water will
rise due to this pressure. The level to which it rises is called the potentiometric
surface. If this surface is above ground level, then the bore will flow. In a
subartesian bore the water does not rise above the ground surface.
Figure 3: The above diagram and text are taken from the Queensland Government
website. The notion of rechargeability from surface waters is wrong and encourages waste,
thereby seriously harming the long term yield of this resource of water, and also the
potential yield of oil and gas in this region. A generation of Australian school children are
copying this false information from the website and into their school projects. The
information is misleading to present users. It reduces the potential value of all economic
activities dependent on the water and petroleum resources of the Basin.
There are several aspects of the Queensland Government diagram which convey a false impression.
It has a greatly exaggerated vertical scale, which is not stated. If the diagram were drawn to a natural
scale it would appear as a single line across the page. The diagram takes no account of the
difference in relative density of the water (1.0) and the rocks (2.6). It carries the implied assumption
that the pressure head of the seepage water from the intake beds, less friction losses all the way,
would be sufficient to overcome the stresses in the rock at the base of the borehole, which is a
physical impossibility.
The sediments are normally consolidated. The water that was in these sediments at the time of
deposition has been slowly squeezed out over geological time. Some of the sediments were derived
from clays, and these consolidate to form strata that are highly impervious, and quite plastic. Such
mudstone rocks can create impervious blankets over vast distances, and this is obviously the case in
the Great Artesian Basin.
Sediments derived from sands consolidate into sandstones. Even though a bed of sand may originally
have an open structure, the processes of consolidation reduce the porosity. Waters derived from the
consolidation of other sediments may enter the free spaces and precipitate other minerals, and the
sand structure deforms under the increasing stresses.
It has been claimed that there are water-bearing porous sandstones at the base of the sedimentary
rocks. Such porous rocks could only exist if the water pressure was quite high, certainly much higher
than any possible pressure from seepage water from the so-called intake beds. The water pressure
would have to comparable to the stresses in the rock, which indicates a plutonic source of the water
from the bedrock below the strata.
THE INTAKE BEDS
The rocks in the so-called recharge areas are sound and impervious. The concept of surface waters
entering these rocks and then percolating underground for hundreds of kilometres is a fallacy.
The Queensland diagram above shows the intake beds as strata lying in an almost vertical direction
with the beds exposed to the rainfall. That is quite misleading. In fact the beds are virtually horizontal
in these areas. The diagram simply reflects the greatly exaggerated vertical scale and some artistic
licence.
As part of my studies of the Great Artesian Basin, I have looked at possible alternative sources of
surface water for town supplies, and even irrigation, in central and Western Queensland. I have
visited some of these so-called recharge areas.
There are sound prospects for inland water diversion from some of the rivers flowing into the Gulf of
Carpentaria. Over one fifth of the runoff of mainland Australia flows into the Gulf. There are several
potential dam and reservoir sites at high level in the upper catchment of the Gulf Rivers. Storages at
high level could command a wide range of potential irrigation areas in the Gulf country and further
south in Queensland, possibly extending to the Queensland parts of the Murray-Darling Basin. With
improved transport, irrigation developments in this area could be quite feasible.
The dam and reservoir sites that I have looked at on the ground are part of the area classified as
recharge areas for surface water to enter the Great Artesian Basin. When I inspected these
prospective damsites recently I observed that the reservoirs would be quite watertight. I could not
understand how people ever imagined that these areas of sound rock would act like a sponge in
soaking up surface water for the Great Artesian Basin.
FLOW THROUGH POROUS MEDIA
One of the obstacles to the conceptual understanding of the behaviour of the Great Artesian Basin is
the prevailing view that the flow regime in deep underground rocks can be described and simulated
by mathematical models based on the Darcy formula for flow through porous media.
Henri Darcy (1803-1858) was a highly capable French engineer who built roads, railways and water
supply systems. As new problems arose in his many projects, he tried to improve his understanding
through research. He was a great hydraulic researcher, and his work became part of the standard
curriculum for teaching hydraulics at the time, and remains so to this day.
The studies by Darcy, in 1856, of the flow of water through sands were initially directed to the design
of sand filters for the Dijon water supply. The Darcy apparatus was quite simple. He used a vertical
iron pipe to contain the sand, and measured the headloss for various discharges and various sizes of
sand.
Darcy found that the velocity of flow was directly proportional to the hydraulic gradient, and that the
constant of proportionality was different for each type of sand that was used.
In the case of flow of water in underground rocks at depth, the size of the flow path is not fixed like in
an iron pipe. There is a balance of forces between the pressures in the water and the stresses in the
rock, and this determines the dimensions of the flow path. The water passages can only remain open
where the water pressure is so great that it is, effectively, holding the rock apart.
It should be noted that this balance of forces of water pressure and rock stress can be quite
independent of the actual volume of water that is present. It is similar in a way to sitting on a rubber
hot water bottle: release some of the water and the pressure remains the same with the smaller
volume of water. This is what has been happening in the Great Artesian Basin: a truly huge volume of
water has been extracted and some borehole pressures remain high. That should never be regarded
as recharging from intake beds hundreds of kilometres away. It simply reflects the great weight of the
super-incumbent rocks acting on the remaining water.
Figure 4: Apparatus used by Darcy
to determine the friction loss for
water passing through sands
contained in an iron pipe. His results
apply to these conditions, that is, flow
within a rigid boundary, independent
of external forces on the boundary.
Figure 5: The Darcy formula has the virtue of
extreme simplicity, and has enabled many
mathematical models to be developed to apply the
concept to the flow of ground-water in a wide range
of field conditions. These models carry an intrinsic
assumption: that the aquifer has a fixed boundary,
independent of internal and external pressures, just
like the iron pipe in the original Darcy experiments of
1856. But the Great Artesian Basin is not made up of
iron pipes.
In my paper on Reservoirs in Naturally Fractured Rock it was explained that the conventional
assumption that deep aquifers occur as porous rock was mostly incorrect, and that the ground-water
flow is properly described as flow through joints and fissures in the rock. My views have obviously cut
across the conventional views of people involved in geohydrology. These conventional views have
been anchored for generations in an implicit faith in the validity of the Darcy law, which is for flow in
porous media, as being applicable for flow in underground rocks. In almost all cases it is just not
applicable.
It is a case of a mathematical model, which was adopted for its simplicity, becoming accepted as
reality. As time has gone by, each generation has forgotten about the assumptions, and built up a
vast range of ground-water studies and reports which often have little relation to reality. This has
happened in the case of the Great Artesian Basin.
These days the mathematical analyses are aided by computer, and computer programmes are
available that show the groundwater flow in three dimensions, and in colour, which adds to the selfdelusion of the users. An internet search of the topic 'groundwater software' reveals the great range of
computer programmes which are now available. These programmes seem to me to be potential traps
for the unwary.
I gather that there are one or two dissenting scholars in the ground-water game who are concerned
about the Darcification of their profession. They should be concerned, and I hope their colleagues
listen.
REVIEW OF EARLY DRILLING
On purely theoretical grounds, it would be expected that the Basin sediments would have been
originally dry over the entire depth to bedrock. In similar sediments worldwide, and at similar depths, it
is not normal to find rocks with open joints or any significant porosity. Consolidation and plastic flow
over time has closed all openings.
But there is water in the strata. When the first bores were drilled, there were gushing bores throwing
fountains of water into the air. What was the source of these waters, and the reasons for the very high
pressures?
In order to resolve these questions, it was necessary for me to go back and review the records of the
early drilling in the Basin. Summary records of all the early bores had been kept by the state
governments, and reproduced in a series of national conferences of the riparian states.
The records for Queensland up to June 1911 showed:
•
•
•
•
•
There were 453 bores.
Maximum depth was 5045 feet. Eleven bores were over 4000 ft deep.
About half the number of bores were taken down through the entire sedimentary sequence
and into the bedrock below.
Waters under sufficient pressure to rise to the surface were mostly found in the bedrock, or in
strata adjacent to the bedrock boundary.
Drilling continued until useful water was found. Sediments were mostly dry over the entire
depth to water.
The data for NSW in records up to June 1914 reveal a similar pattern. The records indicated that the
strata were dry, and that the water was in the bedrock below.
Figure 6: An early drill rig driven by steam power.
The drilling of over 1000 very deep bores in the
first 30 years from 1885 to 1914 was a truly
remarkable achievement, reflecting a level of
investment in rural properties that would not be
possible today. (photo from Qld website on
artesian basin)
SONG OF THE ARTESIAN WATER
I discovered an early poem by A. B. (Banjo) Paterson, the Song of the Artesian Water. It had been
published in The Bulletin, 12 December, 1896. The poem has not been included in some of the
compilations of selected poems by Paterson, and it is not well known. But it sang a song I was
pleased to hear.
It is a time of drought, and the stock have started dying. The drillers have been called in to drill for
water. The driller is a Canadian, and he is driving the engine hard:
But the shaft has started caving,
And the sinking's very slow,............
But there is no artesian water
Though we've passed three thousand feet.
And it's down we've got to go,
Though she's bumping on the bedrock four thousand feet below,
And then,
The whistle's blowing with a wild exultant blast,....
...for they've struck the flow at last,
and it's rushing up the tubing from four thousand feet below.
Although Banjo Paterson had a propensity to tell a good yarn, I suspect there was sufficient natural
drama in these events for Paterson to tell it as it was happening at the time. The poem confirmed my
view that the artesian water originally came from the bedrock and not from within the strata.
INJECTION EFFECTS OF THE FIRST BORES
Having identified that the normal condition of the strata in the Basin was dry prior to the drilling of
bores, the question arose as to how the strata came to be water bearing afterwards. It is evidently due
to the injection into the strata of high-pressure waters from the earlier bores.
This was possible because of the differences in density of the water and the rocks. Water in the
bedrock that was trapped below the impervious blanket of the Basin sediments must have been held
at water pressures approaching the overburden stress of the rock. The early boreholes punctured the
impervious blanket, enabling these high pressure waters to escape to the surface. It would be readily
possible for these high-pressure waters in these deep bores to get behind the staged casing and into
the shallower strata.
Thus there may have been two categories of boreholes:
•
•
Primary Bores, which tapped the water in the bedrock,
Secondary Bores, which found water in shallower strata, and depended on water injected into
these beds from the primary bores.
In these circumstances, it would be expected that the primary boreholes would flow for a longer
period and the secondary boreholes would have a short life.
Now, over 100 years later, there is a very large number of non-flowing bores.
Figure 7: The water pressures
in the first bores were such as
to provide high pressures in the
upper parts of the bores that
would have been greater than
the overburden stress at these
levels. The excess of the water
pressure over the overburden
stress enabled the injection of
water into the shallower strata
by the simple process of
hydraulic jacking.
LATER DRILLING
In the last few decades there has been extensive studies of the region of the Great Artesian Basin for
the purposes of petroleum exploration and production. There seems to have been little mutuality of
interest of the water and petroleum scientists. It was intriguing to note that in a study of petroleum
prospectivity in NSW, reported in 1996, Alder,et al, noted in a section on water bore data, "A
surprisingly large number of water bores in the Surat and Eromanga Basins were drilled to
basement." My comment on that is that the bores were drilled to basement because that was the
source of the artesian water.
Berry and Armstrong (1996) show drilling to basement in their paper on water supply for Olympic Dam
operations.
The boreholes are shown in the accompanying profile, taken from a paper by Berry and Armstrong in
1996. It is noted that all of the boreholes were taken down to basement. Presumably that was the
source of water.
Figure 8: The bores for the water supply operations at Olympic Dam were all taken down to
or near bedrock. It is of interest that the mineral deposits on which the WMC mine is based
could only have been created in the presence of plutonic waters under high temperatures
and pressures.
RESERVOIRS IN NATURALLY FRACTURED ROCKS
If the water was not originally in the sediments, it meant that the source must be in the much older
fractured rocks below the sedimentary series.
I prepared a paper for FOCUS on Reservoirs in Naturally Fractured Rock, suggesting that the oil and
gas found in the region and the artesian water may originate from the same source of fractured rocks
below the Basin. That was obviously too much for some people, even friends.
But the evidence was accumulating. The release of methane in large quantities was associated with
many of the early boreholes. In the early days, the methane released from boreholes was captured in
small pressure vessels. The methane was sometimes flared at night and used as a light and a beacon
for stock mustering. Great quantities of natural gas must have been wasted over the past century.
Nobody was interested.
In 1914, the Government Geologist in Queensland noted that people were not interested in looking for
intake beds for the methane and petroleum. He seems to have been quietly ignored as a cynic.
As natural gas and oil are lighter than water, the association of water and petroleum in the Great
Artesian Basin means that the water is below the petroleum. The petroleum is being driven upwards
by these deeper plutonic waters. This is called a water-drive, a phenomenon often observed in
petroleum reservoirs around the world.
It is of interest to note that in the petroleum industry one of the conventional ways of enhancing the
flow of oil and gas from a petroleum reservoir is to inject water at high pressure into the rocks at the
base of the well. This has the effect of opening fractures in the rock by hydraulic jacking, thereby
enabling the oil and gas to migrate more readily.
In the case of the Great Artesian Basin, exactly the opposite has been done over the past 120 years.
An enormous volume of water and gas has been extracted and mostly wasted, inevitably leading to
the closure of previously open fractures in the rock.
The volume of water taken from the Basin to date is in the magnitude of 100 times the volume of
Sydney Harbour. That volume of water must have been held in open fractures in the rock. As water is
removed the joints inevitably close. Thus the fractures in the rock that once held water have now been
reduced in volume by that amount. This must have had a most damaging effect on the potential
recovery of oil and gas from this region, as well as water.
REGIONAL TECTONICS
The sediments of the Great Artesian Basin constitute a vast impervious and thermal blanket over the
basement rocks over one fifth of Australia. This impervious blanket has acted as a cap to the upward
migration of plutonic waters, and of oil and gas.
The sediments of the Basin have less thermal conductivity than the basement rocks. This means that
these strata are an insulating blanket over the hot rocks below. It is of interest that the hot spots in
Australia are observed in the area of the Great Artesian Basin.
Figure 9: Assessed heat flow for
Australia. Note the strong
concentration of hot spots in the
area of the sedimentary basins,
especially the Great Artesian
Basin. ( after Cull And Conley)
In the paper on Reservoirs in Naturally Fractured Rocks I referred to the work of Emeritus Professor
S. W. Carey on the Expanding Earth. Carey was head of Geology at the University of Tasmania for
many years.
About 40 years ago I was working on designs for an underground power station in Tasmania. As part
of the design process, we measured the residual stresses in the rock. The horizontal rock stress in
one direction was surprisingly high. I had the opportunity to discuss our findings with Professor Carey,
head of geology at the University of Tasmania. Carey quickly assured us that our measurements were
consistent with his understanding of the tectonic behaviour in the region.
Carey outlined his views on Continental Drift, demonstrating on spherical models that the continents
fitted together extra-ordinarily well if they were matched at the edge of the continental shelf, and if the
earth was much smaller in size such that continents occupied the entire crust. Carey had concluded
that the earth was expanding.
It was quite convincing to me, as the evidence was so clear. The trouble was that Prof. Carey, and
everybody else, had no idea of the physical mechanism which could cause the earth to expand. This
led to the world geological community rejecting the Carey concept of an expanding earth, even
though it is much more consistent with the growing knowledge and measurements of the actual
structural behaviour of the crust of the earth.
Carey believes that the earth has been expanding for the past 200 million years or so. Measurements
of the age of the rocks on the ocean floor show that the oceans are expanding laterally by means of
sea-floor spreading, and to a great extent.
Figure 10: Continuing crustal changes over the past 65 million years have created large
new areas of ocean floor on either side of mid-ocean ridges. The commonly accepted view
of this phenomenon is that the continents are drifting and that the earth remains a constant
size. An alternative view, which I prefer, is that the earth is expanding to an extent indicated
by the increasing size of the oceans. A very small annual increase in radius of the Earth of
only 3 to 4 mm per year is compatible with the sea-floor spreading shown on the map.
The region of the Great Artesian Basin can be regarded as one such zone where there has been a
lateral extension in the earth's crust. The sagging basin shape of the Basin is an indication of lateral
extension. The extension is generally in the east-west direction.
The consolidating sediments would have tended to follow the down-warp into the Basin shape without
fracture, remaining as an impervious blanket over the basement rocks.
The hard crustal rocks below the sediment would adjust to the lateral extension by the opening of preexisting fractures, thereby providing paths for rising plutonic water , oil and gas.
Figure 11: Profile of the Great Artesian Basin from Roxby Downs to Blackall. The sag of
the Basin indicates that it is a zone of lateral extension in the crust of the earth. The
contiguous north-south zone of volcanism is also an indication of lateral extension in the
east-west direction. It is the combination of volcanism and lateral extension in the crust of
the Earth that led to the accumulation of plutonic waters under the impervious blanket of the
sedimentary series.
VOLCANISM AND THE GREAT ARTESIAN BASIN
The Great Artesian Basin adjoins a wide north-south zone of volcanism in Australia, extending from
Cape York to Tasmania. It is little recognised that this belt of volcanism extending over the entire
length of eastern Australia is one of the world's most extensive volcanic zones.
The most recently active centres were Mt. Gambier, 4600 years ago, and north Queensland, 13,000
years ago. A north-south line joining these two recently active volcanic centres passes through the
middle of the Great Artesian Basin, and through the hot spots shown in Figure 9. It is reasonable to
think that the great thickness of impervious sediments in the Basin, (2000 metres), would have tended
to inhibit volcanism directly within the Basin. Thus the volcanism adjoins the Basin, but does not
penetrate the sediments.
The north-south zone of volcanism can also be regarded as a zone of crustal extension. It follows the
same linear trend as the Tasman Fracture Zone in the southern ocean between Tasmania and
Antarctica.
The more easterly volcanic provinces vary in age from 6 to 42 million years. The extensive and more
recent lava fields in northern Queensland and Western Victoria are up to 6 million years old.
Figure 12: Volcanic Provinces of Eastern
Australia. These provinces are areas of
volcanism. The actual number of volcanic sites
is very much larger, as indicated in the chart
below showing volcanism in Western Victoria.
Note that these areas of volcanism surround the
Great Artesian Basin on all except the western
side. It is my view that plutonic waters
accumulated under Basin during this period of
volcanism. The most recent centres of volcanism
are Mt. Gambier in South Australia, only 4600
years ago, and northern Queensland, 13,000
years ago.
Figure 13: There are a very large number of small volcanoes in western Victoria, and
extensive lava fields of quite recent age. The eruptions would have been accompanied by
the emission of huge clouds of steam. The plutonic waters are the driving force for volcanic
eruptions. The deeper plutonic waters are held at very high pressures because of the great
weight of the rocks, and at very high temperatures. In a zone of lateral crustal extension,
the deeper waters can rise to shallower depths and release enormous energy on
conversion to steam. A volcano can be regarded as a cannon, with the ballistic propellant
being plutonic waters at high pressures and temperatures.
There is much evidence concerning the waters of the Great Artesian Basin that confirms that the
waters are of plutonic origin. These include the combination of natural gas and water, helium
concentrations, fluoride, and hydrogen sulphide, and the high temperature gradients.
FINDING A FRIEND
I was starting to feel rather alone. I seemed to be the only person in Australia who was saying that the
Great Artesian Basin was definitely not being recharged from surface rainfall. My friends and
colleagues were apprehensive.
I was surprised at the intensity of the opposition, especially at state government levels. Apparently the
Australian Geological Survey Organisation was told to keep out of ground-water studies, as that was
a state responsibility.
And then I found a friend. Although I could only read what he had written, I was greatly impressed and
encouraged.
JOHN WALTER GREGORY, FRS. DSc. (1864-1932)
Gregory began his career as a geological assistant in the British Museum in London in 1887 and
began his academic studies in the evening at the Mechanics Institute. He then went on to the
University of London, where he gained B.Sc. (First class honours) (1891) and D.Sc. (1893).
Working with British Museum, he obtained a very wide
range of geological experience in a few years. In 1891 he
visited the Rocky Mountains and the Great Basin in
America. In 1896 he went as a naturalist on an expedition to
Kenya. The expedition disintegrated and Gregory organised
his own expedition and with 40 Africans covered 1650 miles
in 5 months. He explored the Rift Valley, the nearby
volcanoes ,lava fields, and geothermal springs, and the
glaciers of Mount Kenya. At the same time he was recording
the flora and fauna of the area and the native peoples whom
he met.
His book, "The Great Rift Valley" was published in 1896.
The book reveals a fascinatingly erudite and highly
Figure 14: Professor John Walter
observant explorer. He then went on an expedition to make
Gregory, FRS, DSc.
the first crossing of Spitzbergen and also travelled to the
West Indies. Meanwhile he completed a 3 volume catalogue of the fossil bryozoa held by the
Museum. He became a Fellow of the Royal Society.
In 1899 Gregory was appointed Professor of Geology at the University of Melbourne. His
qualifications for the appointment were so outstanding that the London committee did not interview
any of the other candidates.
The geology of Australia became his new field of exploration, and he travelled widely. In 1901-02 he
took a group of students on a field trip to Lake Eyre and studied the artesian bores. He wrote a book
about this trip, "The Dead Heart of Australia", which was published in 1906.
Chapter 17 of the book is entitled "The Flowing Wells of Central Australia". It is a most scholarly
analysis of the origins of the water. In my studies of the Great Artesian Basin I have looked at many
papers on the subject, but in my opinion the Gregory analysis has an outstanding breadth and
intellectual quality that has not been equalled, in 100 years!
The following are some direct quotations from the book. It reads as if it was written yesterday.
EXTRACTS FROM BOOK by J.W GREGORY, "The Dead Heart of Australia" 1906
"Subterranean water may be derived from one of two sources. Cool water, which occurs at
comparatively slight depths, is no doubt, generally, rain-water ....As this water comes originally from
the sky it is called 'meteoric' water..
The second source of subterranean water is the interior of the earth. The rocks of the deeper layers of
the earth's crust contain water. The quartz in granite owes its milky whiteness to abundant minute
cavities, filled with water. The vast steam cloud, which hangs over volcanoes,...has no doubt been
brought.. from the interior of the earth.
Plutonic waters are especially important in mining countries, because most of the chief ore-deposits
are due to them. And as the deep, water-bearing basin of Central Australia is surrounded on all sides
by rocks containing rich mineral veins - from the Queensland gold-fields on the east, the Cobar
copper-field and Broken Hill in the south, and the Cloncurry god-field in the west -, there is likely to be
a considerable amount of plutonic water under Central Australia.
Where these ascending waters are cut off from the surface by an overlying sheet of clay, they
accumulate in any porous beds they can enter, and remain in them subject to high pressure. Any
plutonic water rising from the old rocks of Central Australia would collect in the permeable beds of
sandstone beneath the clays. Thence it would rush to the surface, if a bore-hole were made through
the water-tight cap above, just as oil and natural gas escape from the wells of the Caspian and
Pennysylvania....
The tendency has always been to assign the origin of the flowing wells to distant localities. The
ancient Egyptians supposed that the water which flowed from the artesian wells of Thebes came from
the hills of Darfur, 700 miles to the south.
The source of the water of the famous well at Grenelle, near Paris, has been attributed to the Jura
Mountains. Is, therefore, only in accordance with precedent, that the source of the deep-well waters of
Lake Eyre should be sought in the mountains of New Guinea, the Andes, and the Himalaya...
The possible origin of Australian artesian water from the Himalayas or New Guinea was suggested,
amongst others, by the Hon. J. T. Murray Prior, in a debate in the Queensland Legislative Council.
"The great question must be", he said, "where does the artesian water come from? The nearest high
mountains we have to Australia are in New Guinea; but still the water may actually come from as far
as the Himalayas under the sea."
The explanation of the flowing wells of Central Australia as due to water-pressure in the distant
Queensland hills is met by many difficulties. One of the chief is, that it under-rates the resistance to
the flow of water through rocks due to friction. The analogy between the geological structure of
eastern Australia and a U-tube fails, because Australia is not built up of tubes. The water has to
percolate, not through open tubes, but through the pores of rocks; and as these rocks are under the
pressure of sometimes as much as four or five thousand feet of overlying material the pores will be
minute.
The average increase of temperature below the surface of the ground is generally taken as 1degree F
for every 53 feet in depth...But many of the flowing wells in Australia show the rate of one degree F for
every twenty-two feet. This high temperature indicates that the water has probably come from a much
greater depth than that of the water-bearing layer. It is, therefore, more likely to be plutonic than
meteoric water...
The association of compressed gas with the artesian waters has been denied or doubted, but it is
admitted that many of the well-waters smell of sulphuretted hydrogen. Many of the Queensland
waters are charged with carbonic acid.
I long hesitated before finally rejecting the ordinary artesian theory of the Central Australian wells, The
question is not merely one of settling a theoretical explanation. It has an important practical bearing.
Many of these wells now run to waste.
This waste is defended on the ground that the water is being renewed at a rate which so vastly
exceeds the outflow from the wells, that they will last for ever without any diminished flow...
Legislation to stop this waste has twice been proposed. A Bill was carried through the Queensland
Assembly in 1891; but the Legislative Council rejected it. In New South Wales a similar Bill was
proposed in 1894, which would have authorised the Water-conservation Department to order the
partial closing of the wells; but it also failed to pass.
Nature has stored up a vast - but probably a limited - supply in a safe, underground reservoir.. But to
allow these deep-well waters - in obedience to a mistaken analogy as to their origin - to run
heedlessly to waste, is a policy of which a later generation of Australians may have bitter cause for
complaint." End of quotes.
Of course, Gregory was quite right. Here we are 100 years later, and we have not yet learned the
simple truths that Gregory explained so clearly.
It is understandable that other people at that time, including geologists, had difficulty in
comprehending such clear statements by Gregory. After all, he was probably the only person in
Australia with such a scientific background in the subject.
In 1904 he left the University of Melbourne for an appointment at the University of Glasgow. His later
books reveal a scholarly range that may not have been achieved had he stayed in Australia. The
debate on the origin of the waters lapsed.
In 1911 there was talk of a five thousand pound prize for the best essay on the origin of the waters,
but it seems that any essay along the lines of thought of Gregory was not likely to win the prize.
CONCLUDING REMARKS FOR FELLOWS
I have concluded that the water in the Great Artesian Basin is of plutonic origin, and probably
accumulated under the impervious blanket of strata of the Basin during 40 million years of recent
volcanic activity in eastern Australia. The pressure of the plutonic waters provides a water drive to the
artesian wells, and also to the oil and gas wells within the Basin.
It is a large but limited resource of residual underground water. The water is stored in fractures in the
bedrock below the strata of the Great Artesian Basin. As a result of the extraction of water to date, the
earlier fractures in the rock have closed by an amount equal to the volume of water removed, which is
a total volume comparable to 100 times the volume of Sydney Harbour. This must have caused an
extensive closure of fractures in the rock, thereby closing flow paths and harming the future yield of
water, and the future yield of oil and gas.
It is probable that the extraction to date has already removed a large part of the stored waters, and an
uncountable volume of natural gas. It remains to be seen whether a smaller sustainable flow of water
is possible.
It is a national economic calamity that such a huge amount of water and natural gas has been wasted
over the past 110 years.
It is a national scientific scandal that so many people who carried responsibilities for the management
of the Great Artesian Basin did not understand the physical characteristics of the Basin. They
contemplated the disturbing evidence of declining flows and closure of bores without comprehension
or action.
When I prepared my first paper on the Basin over a year ago there was an attempt to persuade ATSE
not to publish the paper.
But the episode flashed some warning lights. It showed that scientific inquiry in Australia is not always
free and open. In the case of the origin of the waters in the Great Artesian Basin and its management,
it has taken 100 years to re-open the debate started by Gregory and then only because of my own
studies at my own expense. There is no way my studies would have been acceptable under peer
review and external funding. (I am not putting myself in the same category as Gregory. After all, he
understood the matter 100 years earlier).
Gregory was a true intellectual, comfortable in several disciplines, looking at the whole picture. Our
system these days is not kind to such scholars. The struggle for funds has led to an increasingly
narrower concentration of effort. Yet most of the problems we face are inter-disciplinary in some way.
The activities of our learned societies are becoming increasingly specialised.
There is little learned debate any more. The presentation of any paper, no matter how comprehensive
or substantial, is limited to a 20 minute (or less) time slot in a crowded symposium, competing with
many other papers sometimes extending in number to over 100 papers. Our whole intellectual effort is
thereby directed to performing under a brief spotlight at some conference somewhere. Mostly there is
no discussion, only questions and certainly no speculation. The attendees do not bother to read one
another's papers. All of this breeds triviality
But it is a general phenomenon. We are now having difficulty in rational discussion of any complex
issue, especially if politics are also involved. The Great Artesian Basin is one example, but there are
many others.
References
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L. A. Endersbee, " The Great Artesian Basin of Australia",
L. A. Endersbee, " Reservoirs in Naturally Fractured Rock",
J. W. Gregory, "The Great Rift Valley", John Murray, London, 1896.
J. W. Gregory, "The Dead Heart of Australia", John Murray, London, 1906.
J. W. Gregory, "The Making of the Earth', Williams and Norgate, London,1921.
J. W. Gregory, "The Elements of Economic Geology", Methuen, London, 1928
J.W. Gregory, "Earthquakes and Volcanoes", Benn, London,1929.
L. Sutherland, "The Volcanic Earth", UNSW Press, 1995.
P. A. Evans, "Fluoride Anomalies in Aquifers of Queensland Section of the Great Artesian
Basin and Their Significance" in Mesozoic Geology of Eastern Australian Plate, Geological
Society of Australia, 1996.
Bryan, Constantine, et al. "The Whitsunday Volcanic Province (Cental Queensland) and the
Gippsland/Otway Basins (Victoria): A Comparison of Early Cretaceous Rift-Related VolcanoSedimentary Successions", ibid.
Alder, Bamberry, Pratt, Foss, '"Recent Investigations of the Great Australian Basin in New
South Wales." ibid.
Berry, Armstrong, "Eromanga Basin Water Supply Development for Olympic Dam
Operations" ibid.
Emeritus Professor Endersbee is a civil
engineer and his professional career has
included 27 years in engineering practice
followed by 13 years at Monash University. He
is now a private consultant. His career in
engineering practice included service with the
Snowy Mountains Hydro Electric Authority, the
Hydro Electric Commission of Tasmania and
the United Nations in South East Asia as an
expert on dam design and hydro power
development. His fields of specialisation
include the management of planning and
design of major development projects and
energy engineering. He has been associated
with the design and construction of several
large dams and underground power station projects and other major works in
civil engineering and mining in Australia, Canada, Asia and Africa. He has taken
a special interest in the scientific field of rock mechanics and was a Vice
President of the International Society of Rock Mechanics.
Emeritus Professor Endersbee is a civil engineer and his
professional career has included 27 years in engineering
practice followed by 13 years at Monash University. He is
now a private consultant. His career in engineering
practice included service with the Snowy Mountains
Hydro Electric Authority, the Hydro Electric Commission
of Tasmania and the United Nations in South East Asia
as an expert on dam design and hydro power
development. His fields of specialisation include the
management of planning and design of major
development projects and energy engineering. He has
been associated with the design and construction of
several large dams and underground power station
projects and other major works in civil engineering and
mining in Australia, Canada, Asia and Africa. He has
taken a special interest in the scientific field of rock mechanics and was a Vice President of
the International Society of Rock Mechanics.
Occasional Papers are non-refereed publications prepared by Academy Fellows for
publication on the Academy web site. The views expressed in the above article are
those of the author(s) and do not necessarily represent the views of the Academy.