PHYSICAL FEATURES.
The annual reports issued by the Water Supply Department of Queensland
give detailed accounts of the annual and average rainfall over the whole
of the colony, with the results of boring for artesian water, both
privately and by Government. It is one of the most valuable and
interesting reports issued, and with the rain maps accompanying it,
conveys in a moment an accurate estimate of the average rainfall both on
the coast and in the far interior. Beginning at Mackay, where the
tropical rains commence, and following the coast line to Cape York, the
record is higher than anywhere else in the colony, owing to the near
approach of the high ranges to the coast. The maximum rainfall recorded
in one year is reported at Geraldton, where 211.24 inches fell in 1894;
Cairns can boast of 174.56 inches as its highest rainfall; this occurred
in 1886. At Cape York, the average is 60.87; and at Mackay, 72.73
inches; these numbers give a general indication of the humidity of the
climate on the east coast of North Queensland. As we advance into the
interior a far different climate prevails, and the farther west we go,
the lighter becomes the rainfall, till it would almost appear as if it
scarcely ever rained in some places in the interior, which are not much
raised above the level of the sea. At Birdsville, low down on the
Diamantina River, on the borders of South Australia, the rainfall taken
for three years, amounted to only 5.72 inches, and on the Mulligan,
where for six years an average was taken, it amounted to only 5.77
inches. At Boulia, on the Burke River, the average for nine years was
13.54 inches.
Between these extremes of great dryness and excessive moisture, the
intervening country shows a graduated increase or decrease as one
approaches or recedes from the eastern coast. As very few water-ways
exist to carry off surplus water, the drainage being often imperceptible
to the eye, this seems a merciful dispensation of Nature, as under such
conditions any great rainfall would place the whole country under a sea
of water long enough for all animal life to become extinct. The water
that flows down the usually dry channels of the western rivers
southwards comes from the Gulf watershed, where the rainfall is much
heavier, averaging at Cloncurry 20.80 inches. The amount of rainfall
determines largely the nature of the fauna and flora of a country, and
causes it to vary, even in the same latitudes. Between the high coastal
districts and the vast rolling plains and downs of the interior these
differences are so marked and distinct that they seem like two separate
countries; climate, timber, herbage, and even animal life are so
different in the two regions that it seems extraordinary such contrasts
should exist in the same latitude in one country. All along the east
coast, where the rainfall is heavy, we find forests of splendid hardwood
and scrubs containing cedar and pine of gigantic growth. In the
interior, the timber is as a rule dwarfed, hollow, and crooked; the
principal timbers being the acacia family, such as the gidya, myall,
brigalow, boree, etc. The grasses of the interior adapt themselves to
the climate, and are of a far hardier growth than the coast grasses; one
season without moisture does not impare their wonderful vitality; the
salt bushes are the hardiest of all vegetation in the interior, and are
of the greatest value to pastoralists. Birds are found on the coast that
never visit the interior districts; while the galas and corellas are
never found in a wild state near the coast. During the wet season in the
summer months many seabirds migrate to the interior for a few weeks.
Accompanying the report of the Hydraulic Engineer is a coloured map
showing the sites of artesian bores and tanks and the supposed area of
the lower cretaceous or water-bearing strata, as well as the underlying
impermeable palaeozoic rocks. The whole of Western Queensland may be said
to belong to the lower cretaceous formation; here and there, where it
has not been denuded by the action of the atmosphere, the desert
sandstone may be found overlaying it. The whole of this vast area of
water-bearing rocks has been proved by artesian bores, most of which are
far below the level of the sea. The knowledge of the area of the
water-bearing country in the interior is extending as additional bores
are put down. Some of the bores within the known belt of the water area
have been abandoned owing to causes that may be generally classified as
accidents.
The Government have sunk a number of wells, while hundreds of flowing
bores that now stud the great western country have been put down by
private enterprise. The policy of the Government has been to determine
the area within which artesian water may be hopefully searched for, and
to provide water in arid country or on stock routes, and excellent
results have attended the carrying out of this policy. The Winton bore
is down in the lower cretaceous beds 4,010 feet, it gives a flow of
720,000 gallons of water a day, at a temperature of 192 degs.; the
surface level is 600 feet above the sea; it will take about L8,000 to
cover the total cost of sinking, etc. The Charleville bore has the
largest flow of any Government bore, giving 3,000,000 gallons in the
twenty-four hours, but some bores on Tinenburra, on the Warrego River,
give as much as 4,000,000 gallons. About 800 private bores have been
sunk in search of artesian water in the western area of Queensland; of
these 515 give a total output of 322 millions of gallons in the
twenty-four hours, and the total cost of them amounted to nearly
L2,000.000. This expenditure made within sixteen years, is creditable to
the energy and forethought of the western settlers. Some of the bores
are not overflowing, and the water is raised by pumping, though the
supply is inexhaustible. By the flow of water thus brought to the
surface, the devastating effects of the periodical droughts have been
minimised, and large areas have become available to profitable
occupation that previously were waste country. The flow of this artesian
water from the private and public bores is worth more to Queensland than
a river of gold. They have completely changed the face of the country,
and removed the anxiety of the stock owners towards the end of the
season, when all surface water (except the most permanent lagoons) has
dried up and formed mud traps to catch all weak stock that venture near
them. These tiny perforations of the earth's surface have helped to
solve the difficulty of settlement on the western lands, where we find
the rainfall diminishing as we go further west. As these little threads
of water find their way across the plains and form into small ponds in
the hollows, the wildfowl resort to them as if they were natural waters,
while the bulrushes (typha angustifolia), soon follow and grow in
masses, although these are only to be found round springs, and never in
permanent lagoons or rivers. Some curious features are connected with
the artesian water supply; sometimes the temperature is very high, that
of the Dagworth bore reaching 196 degrees, while the pressure of the
Thargomindah bore is over 230 lbs. to the square inch. The water supply
tapped is perhaps beyond calculation, and up to the present time there
is no indication of exhaustion.
The source of this enormous pressure of water that is capable of sending
a jet over a hundred feet above the surface, is still unexplained, and
many theories are afloat as to its origin; some of these go far afield
for reasons for the great supply and strong pressure. The enormous
rainfall on the coast ranges, where the intake probably occurs, and
where the impermeable rocks approach the surface, carrying the water
under the lower cretaceous, or more recent formation (which is shown to
be the most extensive in Western Queensland), seems to be the most
reasonable to adopt at the present time. These water-bearing strata must
cover very large areas in Australia, for a bore at Tarcanina, near the
south coast on the Great Australian Bight, is down over 1,000 feet below
the level of the sea, and throws the water to a great height above the
surface.
Mr. R. L. Jack, the Government Geologist, in a paper on artesian water
in the western interior of Queensland read before the Australian
Association for the Advancement of Science, in Brisbane, January, 1895,
argues in a most convincing manner as to the source of artesian supplies
of water, giving the intake or gathering ground at about 55,000 square
miles, over a region where the mean average rainfall taken at thirteen
meteorological stations along the line of outcrop, amounts to 27 inches
annually, which is considerably greater than that of the interior of the
downs country. The greater part of the rainfall is not carried away by
the channels of the rivers, neither is it evaporated, but sinks through
porous strata into the earth, and does not return except through springs
or submarine leakage. The fact of all this great supply of water finding
its way to the sea at great depths, shows what little effect a few bores
can have on the enormous annual supply. It is an encouragement to extend
the number of bores, which are so necessary to successfully settle the
arid plains of the distant interior, in order to anticipate the waste of
water.
The fact of an artesian bore diminishing its flow may be due to many
causes other than shortage of supply, faults in the tubing or caving in
of the strata may account for it. We have here the secret of successful
settlement in inland Australia--an inexhaustible supply of water fit for
all the wants of man.
The Normanton bore, practically on the edge of the Gulf, and sunk from a
level of about 30 feet above the sea, struck artesian water at a depth
of 1,983 feet, or 1,950 feet below sea level. This bore and the one at
Burketown, both of which were successful in reaching artesian water,
were put down by the Government during the time Mr. G. Phillips
represented Carpentaria in the Legislative Assembly, 1893-5.
THE GRASSES AND FODDER PLANTS.
An enumeration of all the fodder plants and herbage common to North
Queensland would require a long catalogue, as variety is Nature's law in
this case, and the western soil teems after the wet season with flowers,
herbs, grasses, and fruits all more or less adapted for use as fodder.
The prospect on the wide spreading plains after the early thunder
showers in November and December is very refreshing to the eye that has
been for months staring on the dry stalks of the Mitchell grass, or else
on the brown bare earth. Trailing vines of the melon and cucumber family
spread themselves in profusion, the fruit of which is eagerly sought
after by stock. Convolvolus flowers and vines grow among the young green
grasses, and many varieties of the compositae show in bright yellow their
gleaming flowers, mingled with hibiscus of every hue. The growth of
plant life is marvellous after the fall of soft rain on the warm rich
soil. Portulaca, known as pigweed, is among the first of the plants to
spring up, and grows in great masses; the seeds form a principal article
of food for the birds that frequent the plains, the young plants are
also used by stock, and are not despised by man in an emergency. All
life, vegetable and animal, revives suddenly after the surface of the
earth has been saturated with the life-giving element; frogs and locusts
sing their songs of joy day and night; flies increase beyond
conception, and mosquitoes and sandflies torment to distraction both
man and beast.
On the plains, the first vegetation to spring up is the sensitive plant,
spreading its delicate foliage over the surface, the leaves closing
during the heat of the day, and opening in the evening. The small
creeping plant said to be poisonous to stock (Euphorbia Drummondi),
appears immediately after rain. The climbing vine (Capparis lucida),
which bears a sub-acid fruit not unlike passion fruit, at this time of
year gives out its white flowers and fruit at the same time. The scent
of the innumerable flowers on the plains, the tender herbage, the young
grasses sending their seed stalks several feet high, and all the soil
covered densely with vegetation and herbage suitable for stock present a
picture to the eye, so utterly opposed to that which prevailed but a few
weeks before the advent of the rains, that the spectator can scarcely
believe it to be the same country. The seeds of some plants will remain
dormant for years, and then suddenly spring up in profusion; for
instance, the plant commonly known as peabush, a leguminous annual
(botanically Sesbania aegyptica), has only a periodical growth, and at
such times, varying for many years, it covers the plains in such rank
masses that the stockriders get quite bewildered when searching for
stock through its scrublike density; for several years after this
abundant growth, the plant will scarcely be noticeable; it is said that
every three years is a peabush year, but the writer cannot support the
theory, as he can only call to mind four or five really bad peabush
seasons in a period of thirty years. The seeds which fall to the ground
in great quantities form the sustenance for flocks of pigeons and other
birds, but much seed must also fall down the cracks of the earth and
bide their time for a chance of springing into life. The flowers of this
plant grow in lilac and yellow on the same stalk. Cattle are fond of it
when young, and mustering stock in a peabush year has many extra
difficulties on account of the prolific growth of this intermittent
annual. It will sometimes grow to a height of fifteen feet, and in
swampy places is so dense that it is difficult to keep even a few horses
in sight when driving through it; after it dries and the seeds fall to
the ground, the stalks break off, and the sweep of the water over the
plains during the succeeding year gathers these dry stems against the
trees in enormous masses like small haystacks, and there they remain
until a bushfire reduces them to ashes. The masses of peabush carried
down creeks and watercourses at certain seasons will yet prove a source
of danger to railway and road bridges when such structures come to be
built on the western plains comprising the watersheds of rivers flowing
into the Gulf of Carpentaria. Though peabush grows strongly on flooded
ground, it can be found of a sturdy growth on ridges or high plains or
downs during a favourable year, especially where water lodges between
ridges. It is an ancient and historical plant, for the flowers that
composed the wreath found on an Egyptian mummy of ancient date, when
softened and opened with warm water, were found to be identical with the
flowers of the peabush of the Flinders River and western plains of North
Queensland.
The native pastures have not been improved by the introduction of stock;
the evils of overstocking and the want of bushfires to keep down the
under-growth, have in some districts deteriorated or exterminated some
of the best of the fodder grasses. The best of all indigenous grasses is
known as Mitchell grass, a perennial of strong growth, and capable of
resisting the driest weather; there are many varieties of this grass,
which is found only on the plains and downs of the interior. It
possesses the faculty of shooting green from the old stalks at the
joints, and taking up moisture, renewing its youth again. The Mitchell
grass grows in isolated strong bunches, and its presence is a sure sign
of a fattening country. The following are the best known varieties:--
"Astrebla pectinata," common Mitchell grass, growing in erect tussocks
of two or three feet high.
"A. triticoides," wheat-eared Mitchell grass; this plant is taller and
coarser than the last, attaining a height of four or five feet.
"A curvifolia," or curly Mitchell grass; plant forming erect tufts one
or two feet high, the leaves narrow and much curved.
"A. elymoides," weeping Mitchell grass; plant decumbent, the stems
several feet long.
The blue grass (Andropogon sericeus), is an annual of soft rapid growth,
with a branching seed-stalk that breaks off and is blown by the wind in
masses into waterholes; the blacks use the fine seeds of this grass for
food.
"Anthistiria membranacea," called the Flinders or Barcoo grass, is an
annual of a reddish colour, found all over the western plains. It is
soft and brittle, breaking easily off to fall on the ground, when stock
will pick it up; it makes excellent hay, keeping sweet for years, and is
one of the most fattening grasses.
The varieties of the indigenous grasses that cover the great western
plains are innumerable; all are more or less eaten by stock, even the
triodia or spinifex that is looked on as a desert grass, and of a
formidable and forbidding nature. Spinifex is a very drought-resisting
plant, and in times of great scarcity and extreme drought, when all
other grasses have dried out and been blown away, the spinifex is there
with its erect spiney leaves, possibly bitter to the taste, but still
life sustaining to stock, as has been proved in many a severe drought.
It grows on sandy sterile ridges, and seems to adhere to the latest
geological formation, the sandstone or cainozoic period; it is found on
ridges adjacent to alluvial flats where the richest herbage and grasses
are found in abundance.
Kangaroo grass (Anthistiria ciliata), is found mostly in coastal
districts, and although a good pasture grass when green, it soon dries
and requires burning.
There are two prominent varieties of spear grass in the north, the worst
being the black spear grass (Andropogon contortus), which grows in sandy
spots along the banks of creeks, or on sandy ridges; it is not of much
use as a fodder grass, but becomes a terrible scourge to sheep when ripe
and seeding. The seeds are barbed, and as sharp as needles, and having
once entered the skin they work into the bone, causing intense annoyance
and irritation, and ultimately death. The other spear grass (Andropogon
Kennedeyii), not so dangerous, but of little use to stock, is a
coarse-growing, strong grass, seven or eight feet high, with a reddish
bloom, and strong seeds that penetrate saddlecloths and clothes in
countless hundreds.
Herbage fills the spaces between the tufts of grasses soon after the
rains, and the plains develop a dense growth of pasturage; but after
continued dry seasons, all herbage disappears, and the grasses follow in
time, until very little is left except the roots, and a few of the more
hardy salsolaceous plants. These form a striking feature in the economy
of Nature in the plain country, the salt bushes are ever present in one
variety or another, and help to keep stock in health and condition. The
various species of "Atriplex" abound, and being very drought-resisting,
they are reckoned amongst the most valuable fodder plants. Sir Thomas
Mitchell was the first to make salt bush known after his first
expedition over sixty years ago.
"A. Nummularia," passing under the curious vernacular of "Old Man Salt
Bush," is truly grey enough. Some of these plants have been propagated
in north-west America with great success, turning the barren alkali
lands that were never known to grow anything, into valuable pastures.
Tons of seeds are raised annually for Utah, Arizona, and other States.
In Africa the salt bushes are cultivated from seeds and even cuttings,
and their value is acknowledged everywhere. They endure scorching heat,
live without rains, are eaten by all kinds of stock, proving nutritious
and wholesome to them, are easily raised from seed, and can, with a
little care, be propagated from cuttings.
The blue bush (Chenopodium), is common all over the Gulf of Carpentaria
watershed, growing in swampy spots where water lies; it is a great
favourite with all kinds of stock, and is getting scarce owing to its
being eaten out so much.
Wild rice (Oryza sativa), grows in swampy places throughout the Gulf
country; the grain is well-defined, but small; all stock are fond of it,
when green; it grows to a height of three or four feet. The rice of
commerce is the produce of cultivated varieties of this grass.
Edible shrubs are extremely plentiful, and are of great value when grass
becomes too dry to be nutritive. A peculiar feature in the vegetation of
the western plains is the "roley-poley," which is called in America the
"tumble weed." This is an annual of quick growth after rains, growing in
a spherical form from a common root; when the stem dries, it breaks off
close to the ground, and the ball of dried vegetation is driven by the
winds over the plains at a furious rate, topping the fences, and piling
up against them in masses. It causes the greatest consternation to
horses as it is driven across the downs. It possesses no virtue as a
fodder plant.
FOSSILS OF ANCIENT AUSTRALIA.
The Australian continent has undergone great changes during the past
geological ages, and most probably has been connected in remote times
with part of Asia, and not unlikely with South America by some now
submerged land. But whatever the connection may have been in the very
distant past, it has been shut off from the larger northern land masses
at so remote a period that the higher forms of mammals have not found
their way to it, as in Africa and South America. Great changes have
taken place in the continent itself. It is supposed that, at one time,
in what is called the cretaceous or chalk age, a great sea spread from
the north right across from what is now the Gulf of Carpentaria,
covering immense tracts of level plain country in the interior of
Australia, including Western Queensland, and part of New South Wales, so
that the western half of the continent was separated from the eastern at
least in the northern parts. Gradually the land rose and great lakes
were formed in the interior, especially in the region of Lake Eyre, and
a growth of vegetation sprang up of a more luxuriant type than is to be
found now in those western parts, otherwise the enormous animals, such
as the giant diprotodon, huge extinct kangaroos, birds larger than the
moa, as well as crocodiles and turtles, could never have found
sustenance to multiply in such numbers as their fossil remains testify
they did in nearly every part of central Australia, and in the interior
of North Queensland. In this sea, which washed the base of the mountains
on the west, was deposited the sandy formation which has become the
level inland plains. From some cause so far unknown, the land became
desiccated, the lakes lost their freshness, and became great salt pans,
the vegetation and the animals dependent on it became extinct, until a
dry and arid region was produced, with a river system that fails to
reach the sea, but becomes absorbed in the great sandy interior. The
smaller types of marsupials of a hardier nature and capable of removing
to greater distances for food, maintained their existence, while the
giants of a similar race have left only their bones embedded in the
drift to testify to the mighty changes that Nature has wrought out in
the past ages. Fossil diprotodons of gigantic size and struthious birds
rivalling in stature the New Zealand moa, are found in Central
Australia. At Lake Callabonna in the great salt Lake Eyre basin, there
are hundreds of fossil skeletons of these animals, many of which have
been removed to the Adelaide Museum. In that locality they are found
most frequently on the surface of the dry salt lake, and have been
preserved by a natural coating of carbonate of lime; the bones are found
at various depths.
Nearly the whole of interior Australia, including Western Queensland, is
one vast cemetery of extinct and fossilised species, scattered along the
surface, or buried deep in cement or drifts, and in clays hidden beneath
the present surface formation. The open plains of the Upper Flinders
disclose great deposits of marine fossil shells, belemnites and
ammonites, and also remains of extinct animals. On the Lower Leichhardt
River, in the Gulf of Carpentaria, forty or fifty feet beneath the
alluvial deposits forming the banks of the river, and firmly embedded in
the hard cement, which is an ancient drift formed of water-worn stones
in an ironstone clay, are found the bones of innumerable extinct
gigantic species of animals that found sustenance and multiplied in
enormous numbers over the Gulf country in some far back pre-historic
age. On the Walsh River are found large numbers of fossils, mostly
shells of the ammonite species. The bones that have been buried for
countless ages in these ancient drifts are well preserved, and are not
very dissimilar in appearance to the bones of animals dying recently on
the surrounding plains, although they are completely fossilised and
changed into the appearance of stone. The utter extinction of these
gigantic species, comprising diprotodon, nototherium, and zygomaturus,
and other species, grasseaters and flesheaters alike, can only be
accounted for by a great change of climate, and great and long-continued
droughts, reducing the herbage and causing the remaining living animals
to crowd into the drying-up lagoons and lakes, there to become bogged in
thousands, and die as the stock die in the waterholes after a long
drought. Some of the fossils are those of animals of a gigantic size,
much larger than any existing native animals; the teeth found are twice
the size of an ordinary bullock's, and the jaws carrying them are of
enormous size and strength. There are remains of alligators over thirty
feet long, and turtles of much greater dimensions than any existing in
the present day. The vegetation in the marshes and territory forming
North Queensland must have been of a luxuriant and tropical description
in those days to have supported such large types of marsupials--animals
that would require a more abundant moisture, larger rainfall, and
heavier foliage, than are now to be found on the western slopes of the
ranges. Deeply interesting is the study of the ancient forms of life
that roamed over the densely-wooded marshes of the interior, when the
flora represented a type found now only along the rich alluvial banks of
the rivers on the east coast.
GEOLOGY OF QUEENSLAND.
The following facts are summarised from the geology of Queensland
written by Mr. Daintree, as the result of his investigations, whilst
prosecuting the search for new goldfields on behalf of the Queensland
Government in the northern portion of their territory, as also from the
official reports of the Geologist of Southern Queensland, and other
sources.
The consideration and history of the different formations will be taken
in their sequence of time, as far as the stratified or sedimentary rocks
are concerned. The igneous rocks will be described under the various
groups of Granitic, Trappean, and Volcanic.
_Aqueous_:--
Alluvial (recent).
Alluvial, containing extinct faunas.
Desert sandstone, Cainozoic.
Cretaceous }
Oolitic } Mesozoic
Carbonaceous }
Carboniferous } Palaeozoic
Devonian }
Silurian }
_Metamorphic._
Alluvial.--Fresh-water deposits skirt all the present watercourses, but
the accumulations are insignificant on the eastern watershed, except
near the embouchures of large rivers, such as the Burdekin, Fitzroy,
etc. On the shores of the Gulf of Carpentaria, however, and in the
south-western portions of the colony, where the watercourses have
scarcely any fall, and where in seasons of excessive rain the country is
nearly all inundated, fluviatile deposits are very extensive. Though the
dense lavas of the Upper Burdekin (volcanic outbursts of a late Tertiary
epoch) are traversed by valleys of erosion, in some cases 200 feet deep,
and five miles broad, yet very narrow and shallow alluvial deposits
skirt the immediate margin of the watercourses draining such valleys. It
is only near the mouths of the larger rivers that any extent of alluvium
has been deposited, and even these areas are at the present time in
seasons of excessive rain, liable to inundation, showing that little
upheaval of this portion of Australia has taken place since the last
volcanic disturbances terminated.
The meteorological or climatic conditions during this period were nearly
identical with those of the present time, heavy rains during the summer
months causing violent floods, removing seaward the aerial
decompositions and denuded materials from year to year.
What lapse of time is represented during this period of erosion is a
matter of speculation, but it seems certain that the mollusca of the
present creeks were also the inhabitants of the waters during the whole
period of denudation since the last volcanic eruption.
From the Gulf of Carpentaria in the north, to Darling Downs in the
south, however, the fossil remains of extinct mammalia have been found
in breccias and indurated muds, which are the representatives of the
beds of old watercourses through which the present creeks cut their
channels. At Maryvale Creek, in latitude 19 deg. 30 sec. S., good
sections of these old brecciated alluvia occur. The fossils from this
section, as determined by Professor Owen, are "Diprotodon Australis,
Macropus titan, Thylacoles, Phascolomys, Nototherium," crocodile teeth,
etc.
Imbedded in the same matrix occur several genera of mollusca
undistinguishable from those inhabiting Maryvale Creek.
The fact of these older alluvia forming both the bed and the banks of
the present watercourse, goes to prove that Diprotodon and its allies
inhabited the Queensland valleys when they presented little difference
in physical aspect or elevation from that of the present time. The
crocodile (Crocodilus Australis), however, had then a greater range
inland than it has now. A study of these Diprotodon breccias leads to
the conclusion that the remains are chiefly entombed in what were the
most permanent waterholes in seasons of excessive drought, and that the
animals came there in a weak and exhausted state to drink and die, just
as bullocks do under similar conditions at the present time.
No human bones, flint flakes, or any kind of native weapons have yet
been discovered with the extinct mammalia of Queensland.
CAINOZOIC.
Desert Sandstone.--On the eastern branches of the Upper Flinders and
elsewhere, fine sections are exposed of lava resting on horizontal beds
of coarse grit and conglomerate, which lie in turn unconformably on
olive-coloured and gray shales with interstratified bands and nodules of
argillaceous limestone containing fossils of cretaceous affinities. I
have called this upper conglomerate series "Desert Sandstone," from the
sandy barren character of its disintegrated soil, which makes the term
particularly applicable.
Without doubt, it is the most recent widely-spread stratified deposit
developed in Queensland. The denudation of the "Desert Sandstone" since
it became dry land has been excessive, but there still remains a large
tract "in situ," and all the available evidence tends to show that this
"Desert Sandstone" did at one time cover nearly, if not quite, the whole
of Australia. The journals of the two Gregory's description of the new
settlement of Port Darwin, all bear evidence to the continuity of this
so-called "Desert Sandstone" over all the extended areas investigated by
them.
Augustus Gregory's description of the sandstones of the Victoria River
agrees with those of the "Desert Sandstone" of Queensland, the specimens
from either locality being undistinguishable the one from the other,
while the same barren soil, the same hostile spinifex, the same fatal
poison plant, mark its presence from Perth to Cape York.
In Queensland, the upper beds are ferruginous, white and mottled sandy
clays, the lower being coarse alternating grits and conglomerates; the
extreme observed thickness has not exceeded 400 feet. A characteristic
view of the upper "Desert Sandstone" beds is shown in Betts' Creek, on
the Upper Flinders. Whether these are marine, lacustrine, or estuarine
deposits, there is hardly sufficient evidence to show.
What may be the value of this "Desert Sandstone" for free gold, is at
present unsolved; but the very nature of its deposition seems to
preclude the idea that that metal will be found in paying quantities,
except where direct local abrasion of a rich auriferous veinstone has
furnished the supply.
MESOZOIC.
Cretaceous.--As early as 1866 a suite of fossils was collected by
Messrs. Sutherland and Carson, of Marathon station, Flinders River, and
forwarded for determination to Professor McCoy, in Melbourne. They were
never figured, but his manuscript names are as follows:--
_Reptilia._
Ichthyosaurus Australis. "M'Coy."
Plesiosaurus Sutherlandi.
Plesiosaurus macrospondylus. "M'Coy."
_Cephalopoda._
Ammonites Sutherlandi. "M'Coy."
Ammonites Flindersi. "M'Coy."
Belemnitella diptycha. "M'Coy."
Ancyloceras Flindersi.
_Lamellibranchiata._
Inoceramus Carsoni. "M'Coy."
Inoceramus Sutherlandi. "M'Coy"
(identical with the English species I. Cuvieri).
In company with Mr. Sutherland, who supplied McCoy with the
before-mentioned materials, Mr. R. Daintree visited the Upper Flinders,
and carefully collected the fossils from three localities, viz.,
Marathon station, Hughenden station, and Hughenden cattle station.
At Marathon, which is some forty miles further down the Flinders than
Hughenden, there is, close to the homestead, an outcrop of fine-grained
yellow sandstone, which has been quarried for building purposes, and
below this, to the edge of the waterhole supplying the house, is a
series of sandstones and argillaceous limestones, containing numerous
organic remains. These were submitted to Mr. Etheridge for examination
and correlation, the result of which appears in the appendix to his
work. The Hughenden cattle station is twenty miles further up the
Flinders than the Hughenden head station. Here hundreds of Belemnites
are strewn over the surface of the two ridges which front the cattle
station huts, but they are rarely found in the soft shales which crop
out from under an escarpment of "Desert Sandstone." The lithological
character of these cretaceous strata is such that decomposition is
rapid; the resulting physical aspect being that of vast plains, which
form the principal feature of Queensland scenery west of the Main
Dividing Range; but that the "Desert Sandstone" has extended over all
this country is evidenced by its existence either in the form of
outliers, or as a marked feature "in situ" in all main watersheds, or by
its pebbles of quartz and conglomerate, which are strewn everywhere over
the surface of the plains. The height of the watershed between the
Thomson and Flinders Rivers is locally not more than 1,400 feet above
sea level, and as the former river has to travel as many miles before
reaching the sea, it is easy to understand why, in a country subject to
heavy tropical rains at one period of the year, followed by a long dry
season, the river channels are ill-defined, and vast tracts of country
covered by alluvial deposits. Down the Thomson and its tributaries,
these mesozoic rocks are known to extend, though much obscured by flood
drifts. That this portion of the mesozoic system extends throughout the
whole of Western Queensland to Western Australia is also more than
probable, hidden, however, over large areas by "Desert Sandstone."
* * * * *
Mineral Springs.--There is one other subject of practical interest
connected with the great mesozoic western plains, and that is the
occurrence of hot alkaline springs, which suggest the possibility of
obtaining supplies of water on the artesian principle over some portion
at least of this area.
At Gibson's cattle station, Taldora, on the Saxby River, a tributary of
the Flinders, a spring of hot water rises above the surface of the
plain, and its overflow deposits a white encrustation, which on analysis
by Dr. Flight, under the direction of Professor Maskelyne, afforded:--
Water 27.793
Silica 0.600
Chlorine 3.369
Sodium 2.183
Carbonic Acid 33.735
Soda 31.690
------
99.370
Apart, therefore, from the 5.552 per cent. of chloride of sodium, the
deposit consists of sequi carbonate of soda or native "Trona," and as
such is used by the settlers for culinary purposes, etc.
PALAEOZOIC.
"Carboniferous."--Whilst the affinities of the southern coalfield of
Queensland are mesozoic, a northern field, of even larger extent, has a
distinct fauna more resembling the Palaeozoic Carboniferous areas of
Europe.
The Dawson, Comet, Mackenzie, Isaacs, and Bowen Rivers drain this
carboniferous area; and numerous outcrops of coal have been observed on
these streams. No commercial use, however, has yet been made of any of
these deposits, as the measures generally are too far inland to be made
available until the railway system of the country is extended in that
direction.
"Devonian."--From the southern boundary of Queensland up to latitude 18
deg. S., a series of slates, sandstones, coral limestones, and
conglomerates extend to a distance 200 miles inland; these are sometimes
overlain by coal measures, sometimes by volcanic rocks, and consequently
do not crop out on the surface over such districts. North of latitude 18
deg. S., however, over the Cape York Peninsula, this series (so far as
we have any evidence), is absent, granites and porphyries capped by
"Desert Sandstone" forming the ranges on the eastern, and their abraded
ingredients the sandy ti-tree flats, those on the western side of that
inhospitable tract of country, a never-ending flat of poor
desert-looking sandy ti-tree country, stretching away to the shores of
the Gulf of Carpentaria.
In the limestone bands, which form the lower portion of the series,
corals are very numerous; in fact, the limestones, where little
alteration has taken place, are a mass of aggregated corals; and as this
class of rock has resisted aerial destruction better than the associated
slates and sandstones, the barriers thus formed mark the trend of the
rock system to which they belong, in a very picturesque and decided
manner; their bold, massive, and varied outline chiselled into the most
delicate fretwork by Nature's hand, is relieved by a wealth of
richly-tinted foliage, unknown in the surrounding bush; and the eye
jaded with the monotony of the eternal gum tree turns with delight to
the changing tints and varied scenery presented by these barrier-like
records of the past. This class of country is very much in evidence at
Chillagoe. On the track from the Broken River to the Gilbert diggings,
Devonian rocks several thousand feet thick may be observed, as they are
continuous in dip, without being repeated, for at least five miles
across the strike, with an average inclination of 60 deg.
Although on the Broken River and its tributaries a breadth of thirty
miles with a length of sixty miles, is occupied by a persistent outcrop
of Devonian strata, gold has only been discovered in remunerative
quantities in a small gully, where a trapdyke has penetrated the
Palaeozoic rocks of the district.
The following districts, however, where Devonian rocks prevail, have
been the centres of gold mining enterprise:--Lucky Valley, Talgai,
Gympie, Calliope, Boyne, Morinish, Rosewood, Mount Wyatt, Broken River,
portion of Gilbert.
In every case here cited, the country is traversed by trap rocks of a
peculiar character, either diorite, diabase, or porphyrite; and
tufaceous representatives of these are also found interstratified in the
upper portion of the same formation, and occasionally throughout the
other beds.
At Gympie, the auriferous area is confined to veins traversing a
crystalline diorite, or within a certain limit of its boundary, marked by
the presence of fossiliferous diabase tufas.
Whatever may have been the solvent and precipitant of the nobler metals
in the auriferous veinstones associated with trap intrusions, all other
but hydrothermal action may safely be eliminated, the very nature of the
reefs, composed as they are of alternating layers of a promiscuous
mixture of quartz, calcspar, pyrites, etc., affording unmistakable
evidence on this point. The gold also contained in the trap dykes
themselves is always accompanied by pyrites, both (according to
Daintree), hydrothermal products separating out during the cooling down
of the trap intrusions. Auriferous lodes, occurring in areas where
hydrothermal action has attended trap disturbances of a special
character in Queensland, are generally thin--to be estimated by inches
rather than feet; but taken as a whole they are far richer in gold than
those enclosed by sedimentary rocks.
GRANITIC.
Outcrops of granite extend along the eastern coast of Queensland from
Broad Sound to Cape York, and inland as far as the heads of streams
running direct from the inner coast range to the sea.
Very little rock of this character is met with west and south of the
Dividing Range which separates rivers flowing to the eastern and
northern coast, and those trending south to the Murray or Cooper's
Creek.
The granites of Queensland vary very much in their crystalline texture,
passing from true granites into porphyry and quartz porphyry.
TRAPPEAN.
Much stress has been laid on the value of certain intrusive trap rocks
as specially influencing the production of auriferous veinstones in
Queensland.
The petrology of these may be divided into four type classes:--1.
Pyritous porphyrites and porphyries. 2. Pyritous diroites and diabases.
3. Chrome iron serpentines. 4. Pyritous felsites.
VOLCANIC.
Whilst the older trappean rocks have apparently had so much influence on
the disturbance and fracture of the sedimentary strata older than the
Carboniferous, and by a secondary process have evidently been centres of
mineralising action, the volcanic seem to have played the most important
part in determining the elevation and present physical outline of
north-eastern Queensland. The main outbursts of lava have taken place
along the Dividing Range which separates the eastern and western waters,
and therefore on the line of the highest elevation of the country. The
more northern volcanic areas, are probably contemporaneous with the
upper volcanic series of Victorian geologists, so extensively developed
in the western districts of that colony. These have issued from
well-defined craters still in existence, and are probably of Pliocene
Tertiary age.
The southern areas, viz., Peak and Darling Downs, etc., are older,
agreeing with the lower volcanic of Victoria, which have been ejected
through fissures, and have in no case a very extensive flow beyond the
lines of fracture through which they issued. These may be referred to
the Miocene Tertiary epoch. The rock masses forming both the upper and
lower volcanic are basic in character, and may be all termed or grouped
under the general term "dolorites."
The volcanic soils of Queensland are those best adapted for the grazier
and agriculturist.
To epitomise:--With the exception of the McKinlay Ranges, a line drawn
parallel to the eastern coast, at a distance of 250 miles, would include
all the palaeozoic, metamorphic, granitic, trappean, and volcanic rocks
represented in the colony, both coal groups lying within the same area.
The mesozoic and cainozoic systems occupy the surface area to the
westward. The volcanic rocks follow the line of greatest elevation on
the main watershed at altitudes from 1,500 to 2,000 feet above sea
level. The chief granitic mass extends from Broad Sound to Cape York,
with an occasional capping of "Desert Sandstone." Westward from the
Dividing Range, "Desert Sandstone" and the cretaceous and oolitic groups
alternate one with the other to the extreme limit of the colony.
AREA OF FORMATIONS.
Estimating the entire extent of the colony at 600,000 square miles, a
rough approximation to the areas occupied by the different geological
formations is as follows:--
Square Miles.
Valueless land, "Desert Sandstone" 150,000
Scrubby and thickly timbered
inferior pastoral, { Carbonaceous }
but valuable as containing { Mesozoic and } 24,000
coal, iron ore, &c. { Palaeozoic }
Fair pastoral, and valuable { Devonian }
for its associated minerals { Silurian } 60,000
and metals { Metamorphic }
Fair pastoral Granitic 114,000
Good pastoral { Cretaceous }
{ and Oolitic } 200,000
First-class pastoral and { Alluvial }
agricultural { Volcanic } 52,000
{ Trappean }
-------
600,000
Looking at the matter from an economical point of view, we find that
one-fourth of the Colony of Queensland is valueless, whereas
three-fourths furnish good pastoral land. Of this latter 60,000 square
miles contain extensive and very valuable mines of gold, with numerous
outcrops of copper and lead ores, to which may be added rich deposits of
tin ore; 24,000 square miles are capable of producing illimitable
supplies of coal and iron; 52,000 square miles are, as far as soil is
concerned, best adapted for the agriculturist and squatter. In
conclusion, it may be asserted that there is here a wealth of material
resource which compares favourably with that of any other Australian
colony.
THE GREAT BARRIER REEF.
North Queensland owes one of its chief claims to distinction to its
numerous ports and harbours. In fact, the whole coast from Lady Elliott
Island northwards to Cape York is one large harbour; protected as it is
from the ocean swell by the Great Barrier Reef, a natural breakwater,
extending for nearly a thousand miles, with a depth from ten to twenty
fathoms, and a distance from the main land which varies from twenty to
fifty miles. The sea outside is profoundly deep, and a few islets are
found on the line of reef, also a few ship canals through the Barrier
Reef. "The Great Barrier Reef of Australia; its products and
potentialities," by W. Saville Kent, F.L.S., is a splendid work, and
beautifully illustrated. This work shows the reef to be full of marine
wonders and is intensely interesting; its various forms of life and
marine vegetation would fill volumes. The Great Barrier Coral Reef of
Australia, the marvellous extent of which was first made known by
Captain Cook, is one of the wonders of the universe. Its linear
measurement is no less than 1,250 miles, extending from 9-1/2 deg. of
south latitude to Lady Elliott's Island, the most southern true coral
islet in the chain or system. Its whole area lies within the territorial
jurisdiction of Queensland, and the greater portion in North Queensland
of which it forms one of the most valuable possessions. Raw material to
the value of over L100,000 annually is obtained from the reefs and
waters for exportation. The distance from the main land to the outer
edge or boundary of this gigantic reef varies from ten or twelve miles
to thirty. It is mostly formed of a chain of detached reefs and coral
islets, many submerged or partially exposed at low water, with several
openings, a few of which offer secure passage for large vessels.