General character.
_Physiography._--The salient features of the Australian continent are
its compact outline, the absence of navigable rivers communicating with
the interior, the absence of active volcanoes or snow-capped mountains,
its isolation from other lands, and its antiquity. Some of the most
profound changes that have taken place on this globe occurred in
Mesozoic times, and a great portion of Australia was already dry land
when vast tracts of Europe and Asia were submerged; in this sense,
therefore, Australia has been rightly referred to as one of the oldest
existing land surfaces. It has been described as at once the largest
island and the smallest continent on the globe. The general contours
exemplify the law of geographers in regard to continents, viz. as to
their having a high border around a depressed interior, and the highest
mountains on the side of the greatest ocean. On the N. Australia is
bounded by the Timor Sea, the Arafura Sea and Torres Strait; on the E.
by the Pacific Ocean; on the S. by Bass Strait and the Southern Ocean;
and on the W. by the Indian Ocean. It stands up from the ocean depths in
three fairly well-marked terraces. The basal plain of these terraces is
the bed of the ocean, which on the Pacific side has an average depth of
15,000 ft. From this profound foundation rise Australia, New Guinea and
Melanesia, in varying slopes. The first ledge rising from the ocean
floor has a depth averaging 8000 ft. below sea-level. The outer edge of
this ledge is roughly parallel to the coast of Western Australia, and
more than 150 m. from the land. Round the Australian Bight it continues
parallel to the coast, until south of Spencer Gulf (the basal ledge
still averaging 8000 ft. in depth) it sweeps southwards to lat. 55 deg.,
and forms a submarine promontory 1000 m. long. The edge of the abysmal
area comes close to the eastern coasts of Tasmania and New South Wales,
approaching to within 60 m. of Cape Howe. The terrace closest to the
land, known as the continental shelf, has an average depth of 600 ft.,
and connects Australia, New Guinea, and Tasmania in one unbroken sweep.
Compared with other continents, the Australian continental shelf is
extremely narrow, and there are points on the eastern coast where the
land plunges down to oceanic depths with an abruptness rarely
paralleled. Off the Queensland coast the shelf broadens, its outer edge
being lined by the seaward face of the Great Barrier Reef. From Torres
Strait to Dampier Land the shelf spreads out, and connects Australia
with New Guinea and the Malay Archipelago. An elongation of the shelf to
the south joins Tasmania with the mainland. The vertical relief of the
land above the ocean is a very important factor in determining the
climate as well as the distribution of the fauna and flora of a
continent.
The land mass of Australia rises to a mean height much less than that
of any other continent; and the chief mountain systems are parallel
to, and not far from, the coast-line. Thus, taking the continent as a
whole, it may be described as a plateau, fringed by a low-lying
well-watered coast, with a depressed, and for the most part arid,
interior. A great plain, covering quite 500,000 sq. m., occupies a
position a little to the east of a meridional line bisecting the
continent, and south of the 22nd degree, but portions of it stretch
upwards to the low-lying country south of the Gulf of Carpentaria. The
contour of the continent in latitude 30 deg. 5' is as follows:--a short
strip of coastal plain; then a sharp incline rising to a mountain
range 4000 ft. above sea-level, at a distance of 40 m. from the coast.
From this a gently-sloping plateau extends to almost due north of
Spencer Gulf, at which point its height has fallen almost to
sea-level. Then there is a gentle rise to the low steppes, 500 to 1000
ft. above sea-level. A further gentle rise in the high steppes leads
to the mountains of the West Australian coast, and another strip of
low-lying coastal land to the sea.
With a circumference of 8000 m. Australia presents a contour
wonderfully devoid of inlets from the sea except on its northern
shores, where the coast-line is largely indented. The Gulf of
Carpentaria, situated in the north, is enclosed on the east by the
projection of Cape York, and on the west by Arnheim Land, and forms
the principal bay on the whole coast, measuring about 6 deg. of long.
by 6 deg. of lat. Farther to the west, Van Diemen's Gulf, though much
smaller, forms a better-protected bay, having Melville Island between
it and the ocean; while beyond this, Queen's Channel and Cambridge
Gulf form inlets about 14 deg. 50' S. On the north-west of the
continent the coast-line is much broken, the chief indentations being
Admiralty Gulf, Collier Bay and King Sound, on the shores of Tasman
Land. Western Australia, again, is not favoured with many inlets,
Exmouth Gulf and Shark's Bay being the only bays of any size. The same
remark may be made of the rest of the sea-board; for, with the
exception of Spencer Gulf, the Gulf of St Vincent and Port Phillip on
the south, and Moreton Bay, Hervey Bay and Broad Sound on the east,
the coast-line is singularly uniform. There are, however, numerous
spacious harbours, especially on the eastern coast, which are referred
to in the detailed articles dealing with the different states. The
Great Barrier Reef forms the prominent feature off the north-east
coast of Australia; its extent from north to south is 1200 m., and it
is therefore the greatest of all coral reefs. The channel between the
reef and the coast is in places 70 m. wide and 400 ft. deep. There are
a few clear openings in the outer rampart which the reef presents to
the ocean. These are opposite to the large estuaries of the Queensland
rivers, and might be thought to have been caused by fresh water from
the land. The breaks are, however, some 30 to 90 m. away from land and
more probably were caused by subsidence; the old river-channels known
to exist below sea-level, as well as the former land connexion with
New Guinea, seem to point to the conditions assumed in Darwin's
well-known subsidence theory, and any facts that appear to be
inconsistent with the theory of a steady and prolonged subsidence are
explainable by the assumption of a slight upheaval.
With the exception of Tasmania there are no important islands
belonging geographically to Australia, for New Guinea, Timor and other
islands of the East Indian archipelago, though not removed any great
distance from the continent, do not belong to its system. On the east
coast there are a few small and unimportant islands. In Bass Strait
are Flinders Island, about 800 sq. m. in area, Clarke Island, and a
few other small islands. Kangaroo Island, at the entrance of St
Vincent Gulf, is one of the largest islands on the Australian coast,
measuring 80 m. from east to west with an average width of 20 m.
Numerous small islands lie off the western coast, but none has any
commercial importance. On the north coast are Melville and Bathurst
Islands; the former, which is 75 m. long and 38 m. broad, is fertile
and well watered. These islands are opposite Port Darwin, and to the
westward of the large inlet known as Van Diemen's Gulf. In the Gulf of
Carpentaria are numerous islands, the largest bearing the Dutch name
of Groote Eylandt.
Mountains.
Along the full length of the eastern coast extends a succession of
mountain chains. The vast Cordillera of the Great Dividing Range
originates in the south-eastern corner of the continent, and runs
parallel with and close to the eastern shore, through the states of
Victoria and New South Wales, right up to the far-distant York
Peninsula in Queensland. In Victoria the greatest elevation is reached
in the peaks of Mount Bogong (6508 ft.) and Mount Feathertop (6303
ft.), both of which lie north of the Dividing Range; in the main range
Mount Hotham (6100 ft.) and Mount Cobberas (6025 ft.) are the highest
summits. In New South Wales, but close to the Victorian border, are
found the loftiest peaks of Australia, Mount Kosciusco and Mount
Townsend, rising to heights of 7328 and 7260 ft. respectively. The
range is here called the Muniong, but farther north it receives the
name of Monaro Range; the latter has a much reduced altitude, its
average being only about 2000 ft. As the tableland runs northward it
decreases both in height and width, until it narrows to a few miles
only, with an elevation of scarcely 1500 ft.; under the name of the
Blue Mountains the plateau widens again and increases in altitude, the
chief peaks being Mount Clarence (4000 ft.), Mount Victoria (3525
ft.), and Mount Hay (3270 ft.). The Dividing Range decreases north of
the Blue Mountains, until as a mere ridge it divides the waters of the
coastal rivers from those flowing to the Darling. The mass widens out
once more in the Liverpool Range, where the highest peak, Mount Oxley,
reaches 4500 ft., and farther north, in the New England Range, Ben
Lomond reaches an elevation of 5000 ft. Near the Queensland border,
Mount Lindsay, in the Macpherson Range, rises to a height of 5500 ft.
In the latitude of Brisbane the chain swerves inland; no other peak
north of this reaches higher than Mount Bartle Frere in the Bellenden
Ker Range (5438 ft.). The Southern Ocean system of the Victorian
Dividing Range hardly attains to the dignity of high mountains. An
eastern system in South Australia touches at a few points a height of
3000 ft.; and the Stirling Range, belonging to the south-western
system of South Australia, reaches to 2340 ft. There are no mountains
behind the Great Australian Bight. On the west the Darling Range faces
the Indian Ocean, and extends from Point D'Entrecasteaux to the
Murchison river. North of the Murchison, Mount Augustus and Mount
Bruce, with their connecting highlands, cut off the coastal drainage
from the interior; but no point on the north-west coast reaches a
greater altitude than 4000 ft. Several minor ranges, the topography of
which is little known, extend from Cambridge Gulf, behind a very much
broken coast-line, to Limmen Bight on the Gulf of Carpentaria. Nothing
is more remarkable than the contrast between the aspect of the coastal
ranges on the north-east and on the south-east of the continent. The
higher Australian peaks in the south-east look just what they are, the
worn and denuded stumps of mountains, standing for untold ages above
the sea. Their shoulders are lifted high above the tree-line. Their
summits stand out gaunt and lonely in an unbroken solitude. Having
left the tree-line far behind him, nothing is visible to the traveller
for miles around but barren peaks and torn crags in indescribable
confusion. A verdure of herbage clothes the valleys that have been
scooped from the summits downwards. But there are no perpetual
snow-fields, no glaciers creep down these valleys, and no alpine
hamlets ever appear to break the monotony. The mountains of the
north-east, on the contrary, are clothed to their summits with a rich
and varied flora. Naked crags, when they do appear, lift themselves
from a sea of green, and a tropical vegetation, quite Malaysian in
character, covers everything.
The absence of active volcanoes in Australia is a state of things, in
a geological sense, quite new to the continent. Some of the volcanoes
of the western districts of Victoria have been in eruption probably
subsequent to the advent of the black-fellow. In some instances the
cones are quite intact, and the beds of ash and scoriae are as yet
almost unaffected by denuding agencies. Late in the Tertiary period
vast sheets of lava poured from many points of the Great Dividing
Range of eastern Australia. But it is notable that all recent volcanic
action was confined to a wide belt parallel to the coast. No evidences
of recent lava flows can be found in the interior over the great
alluvial plain, the Lower, or the Higher Steppes. Nor has the
continent, as a whole, in recent times been subjected to any violent
earth tremors; though in 1873, to the north of Lake Amadeus, in
central Australia, Ernest Giles records the occurrence of earthquake
shocks violent enough to dislodge considerable rock masses.
Australia possesses one mountain which, though not a volcano, is a
"burning mountain." This is Mount Wingen, situated in a spur of the
Liverpool Range and close to the town of Scone. Its fires are not
volcanic, but result from the combustion of coal some distance
underground, giving off much smoke and steam; geologists estimate that
the burning has been going on for at least 800 years.
Rivers.
The coastal belt of Australia is everywhere well watered, with the
exception of the country around the Great Australian Bight and Spencer
Gulf. Flowing into the Pacific Ocean on the east coast there are some
fine rivers, but the majority have short and rapid courses. In
Queensland a succession of rivers falls into the Pacific from Cape
York to the southern boundary of the state. The Burdekin is the finest
of these, draining an area of 53,500 sq. m., and emptying into Upstart
Bay; it receives numerous tributaries in its course, and carries a
large body of fresh water even in the driest seasons. The Fitzroy
river is the second in point of size; it drains an area of 55,600 sq.
m., and receives several tributary streams during its course to Keppel
Bay. The Brisbane river, falling into Moreton Bay, is important
chiefly from the fact that the city of Brisbane is situated on its
banks. In New South Wales there are several important rivers, the
largest of which is the Hunter, draining 11,000 sq. m., and having a
course of 200 m. Taking them from north to south, the principal rivers
are the Richmond, Clarence, Macleay, Hastings, Manning, Hunter,
Hawkesbury and Shoalhaven. The Snowy river has the greater part of its
course in New South Wales, but its mouth and the last 120 m. are in
Victoria. The other rivers worth mentioning are the Yarra, entering
the sea at Port Phillip, Hopkins and Glenelg. The Murray (q.v.), the
greatest river of Australia, debouches into Lake Alexandrina, and
thence into the sea at Encounter Bay in South Australia. There are no
other rivers of importance in South Australia, but the Torrens and the
Gawler may be mentioned. Westward of South Australia, on the shores of
the Australian Bight, there is a stretch of country 300 m. in length
unpierced by any streams, large or small, but west of the bight,
towards Cape Leeuwin, some small rivers enter the sea. The south-west
coast is watered by a few streams, but none of any size; amongst these
is the Swan, upon which Perth, the capital of Western Australia, is
built. Between the Swan and North-West Cape the principal rivers are
the Greenough, Murchison and Gascoyne; on the north-west coast, the
Ashburton, Fortescue and De Grey; and in the Kimberley district, the
Fitzroy, Panton, Prince Regent and the Ord. In the Northern Territory
are several fine rivers. The Victoria river is navigable for large
vessels for a distance of about 43 m. from the sea, and small vessels
may ascend for another 80 m. The Fitzmaurice, discharging into the
estuary of the Victoria, is also a large stream. The Daly, which in
its upper course is called the Katherine, is navigable for a
considerable distance, and small vessels are able to ascend over 100
m. The Adelaide, discharging into Adam Bay, has been navigated by
large vessels for about 38 m., and small vessels ascend still farther.
The South Alligator river, flowing into Van Diemen's Gulf, is also a
fine stream, navigable for over 30 m. by large vessels; the East
Alligator river, falling into the same gulf, has been navigated for 40
m. Besides those mentioned, there are a number of smaller rivers
discharging on the north coast, and on the west shore of the Gulf of
Carpentaria the Roper river discharges itself into Limmen Bight. The
Roper is a magnificent stream, navigable for about 75 or 80 m. by
vessels of the largest tonnage, and light draught vessels can ascend
20 m. farther. Along the portion of the south shore of the Gulf of
Carpentaria which belongs to Queensland and the east coast, many large
rivers discharge their waters, amongst them the Norman, Flinders,
Leichhardt, Albert and Gregory on the southern shore, and the Batavia,
Archer, Coleman, Mitchell, Staaten and Gilbert on the eastern shore.
The rivers flowing into the Gulf of Carpentaria, as well as those in
the Northern Territory, drain country which is subject to regular
monsoonal rains, and have the general characteristics of sub-tropical
rivers.
The network of streams forming the tributaries of the Darling and
Murray system give an idea of a well-watered country. The so-called
rivers have a strong flow only after heavy rains, and some of them do
not ever reach the main drainage line. Flood waters disappear often
within a distance of a few miles, being absorbed by porous soil,
stretches of sand, and sometimes by the underlying bed-rocks. In many
cases the rivers as they approach the main stream break up into
numerous branches, or spread their waters over vast flats. This is
especially the case with the tributaries of the Darling on its left
bank, where in seasons of great rains these rivers overspread their
banks and flood the flat country for miles around and thus reach the
main stream. Lieutenant John Oxley went down the Lachlan (1817) during
one of these periods of flood, and the great plains appeared to him to
be the fringe of a vast inland sea. As a matter of fact, they are an
alluvial deposit spread out by the same flood waters. The great rivers
of Australia, draining inland, carve out valleys, dissolve limestone,
and spread out their deposit over the plains when the waters become
too sluggish to bear their burden farther. From a geological
standpoint, the Great Australian Plain and the fertile valley of the
Nile have had a similar origin. Taking the Lachlan as one type of
Australian river, we find it takes its rise amongst the precipitous
and almost unexplored valleys of the Great Dividing Range. With the
help of its tributaries it acts as a denuding agent for 14,000 sq. m.
of country, and carries its burden of sediment westwards. A point is
reached about 200 m. from the Dividing Range, where the river ceases
to act as a denuding agent, and the area of deposition begins, at a
level of 250 ft. above the sea, but before the waters can reach the
ocean they have still to travel about 1000 m.
The Darling is reckoned amongst the longest rivers in the world, for
it is navigable, part of the year, from Walgett to its confluence with
the Murray, 1758 m., and then to the sea, a further distance of 587
m.--making in all 2345 m. of navigable water. But this gives no
correct idea of the true character of the Darling, for it can hardly
be said to drain its own watershed. From the sources of its various
tributaries to the town of Bourke, the river may be described as
draining a watershed. But from Bourke to the sea, 550 m. in a direct
line, the river gives rather than receives water from the country it
flows through.
The annual rainfall and the area of the catchment afford no measure
whatever as to the size of a river in the interior of Australia. The
discharge of the Darling river at Bourke does not amount to more than
10% of the rainfall over the country which it drains. It was this
remarkable fact which first led to the idea that, as the rainfall
could not be accounted for either by evaporation or by the river
discharge, much of the 90% unaccounted for must sink into the ground,
and in part be absorbed by some underlying bed-rock. All Australian
rivers, except the Murray and the Murrumbidgee, depend entirely and
directly on the rainfall. They are flooded after rain, and in seasons
of drought many of them, especially the tributaries of the Darling,
become chains of ponds. Springs which would equalize the discharge of
rivers by continuing to pour water into their beds after the rainy
season has passed seem entirely absent in the interior. Nor are there
any snowfields to feed rivers, as in the other continents. More
remarkable still, over large tracts of country the water seems
disposed to flow away from, rather than to, the river-beds. As the
low-lying plains are altogether an alluvial deposit, the coarser
sediments accumulate in the regions where the river first overflows
its banks to spread out over the plains. The country nearest the river
receiving the heaviest deposit becomes in this way the highest ground,
and so continues until a "break-away" occurs, when a new river-bed is
formed, and the same process of deposition and accumulation is
repeated. As the general level of the country is raised by successive
alluvial deposits, the more ancient river-beds become buried, but
being still connected with the newer rivers at some point or other,
they continue to absorb water. This underground network of old
river-beds underlying the great alluvial plains must be filled to
repletion before flood waters will flow over the surface. It is not
surprising, therefore, that comparatively little of the rainfall over
the vast extent of the great central plain ever reaches the sea by way
of the river systems; indeed these systems as usually shown on the
maps leave a false impression as to the actual condition of things.
Steppes.
Lakes.
The great alluvial plain is one of Australia's most notable inland
features; its extent is upwards of 500,000 sq. m., lying east of 135
deg. W. and extending right across the continent from the Gulf of
Carpentaria to the Murray river. The interior of the continent west of
135 deg. and north of the Musgrave ranges is usually termed by
geographers the Australian Steppes. It is entirely different in all
essential features from the great alluvial plains. Its prevailing
aspect is characterized by flat and terraced hills, capped by desert
sandstone, with stone-covered flats stretching over long distances.
The country round Lake Eyre, where some of the land is actually below
sea-level, comes under this heading. The higher steppes, as far as
they are known, consist of Ordovician and Cambrian rocks, with an
average elevation of 1500 to 3000 ft. above sea-level. Over this
country water-courses are shown on maps. These run in wet seasons, but
in every instance for a short distance only, and sooner or later they
are lost in sand-hills, where their waters disappear and a line of
stunted gum-trees (_Eucalyptus rostrata_) is all that is present to
indicate that there may be even a soakage to mark the abandoned
course. The steppes cover a surface of 400,000 sq. m., and from this
vast expanse not a drop of the scanty rainfall reaches the sea; there
is no leading drainage system and there are no rivers. Another notable
feature of the interior is the so-called lake area, a district
stretching to the north of Spencer Gulf. These lakes are expanses of
brackish waters that spread or contract as the season is one of
drought or rain. In seasons of drought they are hardly more than
swamps and mud flats, which for a time may become a grassy plain, or
desolate coast encrusted with salt. The country around is the
dreariest imaginable, the surface is a dead level, there is no heavy
timber and practically no settlement. Lake Torrens, the largest of
these depressions, sometimes forms a sheet of water 100 m. in length.
To the north again stretches Lake Eyre, and to the west Lake Gairdner.
Some of these lake-beds are at or slightly below sea-level, so that a
very slight depression of the land to the south of them would connect
much of the interior with the Southern Ocean. (T. A. C.)
_Geology._--The states of Australia are divided by natural boundaries,
which separate geographical areas having different characters, owing,
mainly, to their different geological structures. Hence the general
stratigraphical geology can be most conveniently summarized for each
state separately, dealing here with the geological history of
Australia as a whole. Australia is essentially the fragment of a great
plateau land of Archean rocks. It consists in the main of an Archean
block or "coign," which still occupies nearly the whole of the western
half of the continent, outcrops in north-eastern Queensland, forms the
foundation of southern New South Wales and eastern Victoria, and is
exposed in western Victoria, in Tasmania, and in the western flank of
the Southern Alps of New Zealand. These areas of Archean rocks were
doubtless once continuous. But they have been separated by the
foundering of the Coral Sea and the Tasman Sea, which divided the
continent of Australia from the islands of the Australasian festoon;
and the foundering of the band across Australia, from the Gulf of
Carpentaria, through western Queensland and western New South Wales,
to the lower basin of the Murray, has separated the Archean areas of
eastern and western Australia. The breaking up of the old Archean
foundation block began in Cambrian and Ordovician times. A narrow
Cambrian sea must have extended across central Australia from the
Kimberley Goldfield in the north-west, through Tempe Downs and the
Macdonnell chain in central Australia, to the South Australian
highlands, central Victoria at Mansfield, and northern Tasmania.
Cambrian rocks occur in each of these districts, and they are best
developed in the South Australian highlands, where they include a long
belt of contemporary glacial deposits. Marine Ordovician rocks were
deposited along the same general course. They are best developed in
the Macdonnell chain in central Australia and in Victoria, where the
fullest sequence is known; while they also extended north-eastward
from Victoria into New South Wales, where, as yet, no Cambrian rocks
have been found. The Silurian system was marked by the retreat of the
sea from central Australia; but the sea still covered a band across
Victoria, from the coast to the Murray basin, passing to the east of
Melbourne. This Silurian sea was less extensive than the Ordovician in
Victoria; but it appears to have been wider in New South Wales and in
Queensland. The best Silurian sequence is in New South Wales. Silurian
rocks are well developed in western Tasmania, and the Silurian sea
must have washed the south-western corner of the continent, if the
rocks of the Stirling Range be rightly identified as of this age.
[Illustration: Geological map of Australia.]
The Devonian system includes a complex series of deposits, which are
of most interest in eastern Australia. This period was marked by
intense earth movements, which affected the whole of the east
Australian highlands. The Lower Devonian beds are in the main
terrestrial, or coarse littoral deposits, and volcanic rocks. The
Middle Devonian was marked by the same great transgression as in
Europe and America; it produced inland seas, extending into Victoria,
New South Wales and Queensland, in which were deposited limestones
with a rich coral fauna. The Upper Devonian was a period of marine
retreat; the crustal disturbances of the Lower Devonian were renewed
and great quartz-pebble beaches were formed on the rising shore lines,
producing the West Coast Range conglomerates of Tasmania, and the
similar rocks to the south-east of Mansfield in Victoria. Intrusions
of granitic _massifs_ in the Devonian period formed the primitive
mountain axis of Victoria, which extends east and west across the
state and forms the nucleus of the Victorian highlands. Similar
granitic intrusions occurred in New South Wales and Queensland, and
built up a mountain chain, which ran north and south across the
continent; its worn-down stumps now form the east Australian
highlands.
The Carboniferous period began with a marine transgression, enabling
limestones to form in Tasmania and New South Wales; and at the same
time the sea first got in along the western edge of the western
plateau, depositing the Carboniferous rocks of the Gascoyne basin and
the coastal plain of north-western Australia. The Upper Carboniferous
period was in the main terrestrial, and during it were laid down the
coal-seams of New South Wales; they are best developed in the basin of
the Hunter river, and they extend southward, covered by Mesozoic
deposits, beyond Sydney. The Coal Measures become narrower in the
south, until, owing to the eastward projection of the highlands, the
Lower Palaeozoic rocks reach the coast. The coal-seams must have been
formed in well-watered, lowland forests, at the foot of a high
mountain range, built up by the Devonian earth movements. The
mountains both in Victoria and New South Wales were snow-capped, and
glaciers flowed down their flanks and laid down Carboniferous glacial
deposits, which are still preserved in basins that flank the mountain
ranges, such as the famous conglomerates of Bacchus Marsh, Heathcote
and the Loddon valley in Victoria, and of Branxton and other
localities in New South Wales. The age of the glacial deposits is
later than the _Glossopteris_ flora and occurs early in the time of
the _Gangamopteris_ flora. Kitson's work in Tasmania shows that there
also the glacial beds may be correlated with the lower or Greta Coal
Measures of New South Wales.
The Permian deposits are best developed in New South Wales and
Tasmania, where their characters show the continuation of the
Carboniferous conditions. The Mesozoic begins with a Triassic land
period in the mainland of Australia; while the islands of the
Australasian festoon contain the Triassic marine limestones, which
fringe the whole of the Pacific. The Triassic beds are best known in
New South Wales, where round Sydney they include a series of
sandstones and shales. They also occur in northern Tasmania.
The Jurassic system is represented by two types. In Victoria,
Tasmania, northern New South Wales and Queensland, there are Jurassic
terrestrial deposits, containing the coal seams of Victoria, of the
Clarence basin of north-eastern New South Wales, and of the Ipswich
series in Queensland; the same beds range far inland on the western
slopes of the east Australian highlands in New South Wales and
Queensland and they occur, with coal-seams, at Leigh's Creek, at the
northern foot of the South Australian highlands. They are also
preserved in basins on the western plateau, as shown by brown coal
deposits passed through in the Lake Phillipson bore. The second and
marine type of the Jurassics occurs in Western Australia, on the
coastal plain skirting the western foot of the western plateau.
The Cretaceous period was initiated by the subsidence of a large area
to the south of the Gulf of Carpentaria, whereby a Lower Cretaceous
sea spread southward, across western Queensland, western New South
Wales and the north-eastern districts of South Australia. In this sea
were laid down the shales of the Rolling Downs formation. The sea does
not appear to have extended completely across Australia, breaking it
into halves, for a projection from the Archean plateau of Western
Australia extended as far east as the South Australian highlands, and
thence probably continued eastward, till it joined the Victorian
highlands. The Cretaceous sea gradually receded and the plains of the
Rolling Downs formation formed on its floor were covered by the
sub-aerial and lacustrine deposits of the Desert Sandstone.
The Kainozoic period opened with fresh earth movements, the most
striking evidence of which are the volcanic outbreaks all round the
Australian coasts. These movements in the south-east formed the Great
Valley of Victoria, which traverses nearly the whole of the state
between the Victorian highlands to the north, and the Jurassic
sandstones of the Otway Ranges and the hills of south Gippsland. In
this valley were laid down, either in Eocene or Oligocene times, a
great series of lake beds and thick accumulations of brown coal.
Similar deposits, of approximately the same age, occur in Tasmania and
New Zealand; and at about the same time there began the Kainozoic
volcanic period of Australasia. The first eruptions piled up huge
domes of lavas rich in soda, including the geburite-dacites and
solvsbergites of Mount Macedon in Victoria, and the kenyte and
tephrite domes of Dunedin, in New Zealand. These rocks were followed
by the outpouring of the extensive older basalts in the Great Valley
of Victoria and on the highlands of eastern Victoria, and also in New
South Wales and Queensland. Then followed a marine transgression along
most of the southern coast of Australia. The sea encroached far on the
land from the Great Australian Bight and there formed the limestones
of the Nullarbor Plains. The sea extended up the Murray basin into the
western plains of New South Wales. Farther east the sea was
interrupted by the still existing land-connexion between Tasmania and
Victoria; but beyond it, the marine deposits are found again, fringing
the coasts of eastern Gippsland and Croajingolong. These marine
deposits are not found anywhere along the eastern coast of Australia;
but they occur, and reach about the same height above sea-level, in
New Guinea, and are widely developed in New Zealand. No doubt eastern
Australia then extended far out into the Tasman Sea. The great
monoclinal fold which formed the eastern face of the east Australian
highlands, west of Sydney, is of later age. After this marine period
was brought to a close the sea retreated. Tasmania and Victoria were
separated by the foundering of Bass Strait, and at the same time the
formation of the rift valley of Spencer Gulf, and Lake Torrens,
isolated the South Australian highlands from the Eyre Peninsula and
the Westralian plateau. Earth movements are still taking place both
along Bass Strait and the Great Valley of South Australia, and
apparently along the whole length of the southern coast of Australia.
_The Flowing Wells of Central Australia._--The clays of the Rolling
Downs formation overlie a series of sands and drifts, saturated with
water under high pressure, which discharges at the surface as a
flowing well, when a borehole pierces the impermeable cover. The first
of these wells was opened at Kallara in the west of New South Wales in
1880. In 1882, Dr W.L. Jack concluded that western Queensland might be
a deep artesian basin. The Blackhall bore, put down at his advice from
1885 to 1888, reached a water-bearing layer at the depth of 1645 ft.
and discharged 291,000 gallons a day. It was the first of the deep
artesian wells of the continent. As the plains on the Rolling Downs
formation are mostly waterless, the discovery of this deep reservoir
of water has been of great aid in the development of central
Australia. In Queensland to the 30th of June 1904, 973 wells had been
sunk, of which 596 were flowing wells, and the total flow was
62,635,722 cub. ft. a day. The deepest well is that at Whitewood, 5046
ft. deep. In New South Wales by the 30th of June 1903, the government
had put down 101 bores producing 66 flowing wells and 22 sub-artesian
wells, with a total discharge of 54,000,000 gallons a day; and there
were also 144 successful private wells. In South Australia there are
38 deep bores, from 20 of which there is a flow of 6,250,000 gallons a
day.
The wells were first called artesian in the belief that the ascent of
the water in them was due to the hydrostatic pressure of water at a
higher level in the Queensland hills. The well-water was supposed to
have percolated underground, through the Blythesdale Braystone, which
outcrops in patches on the eastern edge of the Rolling Downs
formation. But the Blythesdale Braystone is a small local formation,
unable to supply all the wells that have been sunk; and many of the
wells derive their water from the Jurassic shales and mudstones. The
difference in level between the outcrop of the assumed eastern intake
and of the wells is often so small, in comparison with their distance
apart, that the friction would completely sop up the whole of the
available hydrostatic head. Many of the well-waters contain gases;
thus the town of Roma is lighted by natural gas which escapes from its
well. The chemical characters of the well-waters, the irregular
distribution of the water-pressure, the distribution of the
underground thermal gradients, and the occurrence in some of the wells
of a tidal rise and fall of a varying period, are facts which are not
explained on the simple hydrostatic theory. J.W. Gregory has
maintained (_Dead Heart of Australia_, 1906, pp. 273-341) that the
ascent of water in these wells is due to the tension of the included
gases and the pressure of overlying sheets of rocks, and that some of
the water is of plutonic origin.[1] (J. W. G.)
_Climate._--The Australian continent, extending over 28 deg. of
latitude, might be expected to show a considerable diversity of climate.
In reality, however, it experiences fewer climatic variations than the
other great continents, owing to its distance (28 deg.) from the
Antarctic circle and (11 deg.) from the equator. There is, besides, a
powerful determining cause in the uniform character and undivided extent
of its dry interior. The plains and steppes already described lie either
within or close to the tropics. They present to the fierce play of the
sun almost a level surface, so that during the day that surface becomes
intensely heated and at night gives off its heat by radiation.
Ordinarily the alternate expansion and contraction of the atmosphere
which takes place under such circumstances would draw in a supply of
moisture from the ocean, but the heated interior, covering some 900,000
sq. m., is so immense, that the moist air from the ocean does not come
in sufficient supply, nor are there mountain chains to intercept the
clouds which from time to time are formed; so that two-fifths of
Australia, comprising a region stretching from the Australian Bight to
20 deg. S. and from 117 deg. to 142 deg. E., receives less than an
average of 10 in. of rain throughout the year, and a considerable
portion of this region has less than 5 in. No part of Victoria and very
little of Queensland and New South Wales lie within this area. The rest
of the continent may be considered as well watered. The north-west
coast, particularly the portions north of Cambridge Gulf and the shores
of the Gulf of Carpentaria, are favoured with an annual visitation of
the monsoon from December to March, penetrating as far as 500 m. into
the continent, and sweeping sometimes across western and southern
Queensland to the northern interior of New South Wales. It is this
tropical downpour that fills and floods the rivers flowing into Lake
Eyre and those falling into the Darling on its right bank. The whole of
the east coast of the continent is well watered. From Cape York almost
to the tropic of Capricorn the rainfall exceeds 50 in. and ranges to
over 70 in. At Brisbane the fall is 50 in., and portions of the New
South Wales coast receive a like quantity, but speaking generally the
fall is from 30 in. to 40 in. The southern shores of the continent
receive much less rain. From Cape Howe to Melbourne the fall may be
taken at from 30 in. to 40 in., Melbourne itself having an average of
25.6 in. West of Port Phillip the fall is less, averaging 20 in. to 30
in., diminishing greatly away from the coast. Along the shores of
Encounter Bay and St Vincent and Spencer Gulfs, the precipitation ranges
from 10 to 20 in., the yearly rainfall at Adelaide is a little less than
21 in., while the head of Spencer Gulf is within the 5 to 10 in.
district. The rest of the southern coast west as far as 124 deg. E.,
with the exception of the southern projection of Eyre Peninsula, which
receives from 10 to 20 in., belongs to the district with from 5 to 10
in. annual rainfall. The south-western angle of the continent, bounded
by a line drawn diagonally from Jurien river to Cape Riche, has an
average of from 30 to 40 in. annual rainfall, diminishing to about 20 to
30 in. in the country along the diagonal line. The remainder of the
south and west coast from 124 deg. E. to York Sound in the Kimberley
district for a distance of some 150 m. inland has a fall ranging from 10
to 20 in. The 10 to 20 in. rainfall band circles across the continent
through the middle of the Northern Territory, embraces the entire centre
and south-west of Queensland, with the exception of the extreme
south-western angle of the state, and includes the whole of the interior
of New South Wales to a line about 200 m. from the coast, as well as the
western and northern portions of Victoria and South Australia south of
the Murray.
The area of Australia subject to a rainfall of from 10 to 20 in. is
843,000 sq. m. On the seaward side of this area in the north and east
is the 20 to 30 in. annual rainfall area, and still nearer the sea are
the exceptionally well-watered districts. The following table shows
the area of the rainfall zones in square miles:--
Rainfall Area
Rainfall. in sq. m.
Under 10 inches 1,219,600
10 to 20 " 843,100
20 to 30 " 399,900
30 to 40 " 225,700
40 to 50 " 140,300
50 to 60 " 47,900
60 to 70 " 56,100
Over 70 " 14,100
---------
Total 2,946,700
The tropic of Capricorn divides Australia into two parts. Of these the
northern or intertropical portion contains 1,145,000 sq. m.,
comprising half of Queensland, the Northern Territory, and the
north-western divisions of Western Australia. The whole of New South
Wales, Victoria and South Australia proper, half of Queensland, and
more than half of Western Australia, comprising 1,801,700 sq. m., are
without the tropics. In a region so extensive very great varieties of
climate are naturally to be expected, but it may be stated as a
general law that the climate of Australia is milder than that of
corresponding lands in the northern hemisphere. During July, which is
the coldest month in southern latitudes, one-half of Australia has a
mean temperature ranging from 45 deg. to 61 deg., and the other half
from 62 deg. to 80 deg. The following are the areas subject to the
various average temperatures during the month referred to:--
Temperature Area
Fahr. in sq. m.
45 deg.-50 deg. 18,800
50 deg.-55 deg. 506,300
55 deg.-60 deg. 681,800
60 deg.-65 deg. 834,400
65 deg.-70 deg. 515,000
70 deg.-75 deg. 275,900
75 deg.-80 deg. 24,500
The temperature in December ranges from 60 deg. to above 95 deg.
Fahr., half of Australia having a mean temperature below 84 deg.
Dividing the land into zones of average summer temperature, the
following are the areas which would fall to each:--
Temperature Area
Fahr. in sq. m.
60 deg.-65 deg. 67,800
65 deg.-70 deg. 63,700
70 deg.-75 deg. 352,300
75 deg.-80 deg. 439,200
80 deg.-85 deg. 733,600
85 deg.-90 deg. 570,600
90 deg.-95 deg. 584,100
95 deg. and over 135,400
Judging from the figures just given, it must be conceded that a
considerable area of the continent is not adapted for colonization by
European races. The region with a mean summer temperature in excess of
95 deg. Fahr. is the interior of the Northern Territory north of the
20th parallel; and the whole of the country, excepting the seaboard,
lying between the meridians of 120 deg. and 140 deg., and north of the
25th parallel, has a mean temperature in excess of 90 deg. Fahr.
Queensland.
The area of Australia is so large that the characteristics of its
climate will not be understood without reference to the individual
states. About one-half of the colony of Queensland lies in the
tropics, the remaining area lying between the tropic and 29 deg. S.
The temperature, however, has a daily range less than that of other
countries under the same isothermal lines. This circumstance is due to
the sea-breezes, which blow with great regularity, and temper what
would otherwise be an excessive heat. The hot winds which prevail
during the summer in some of the other colonies are unknown in
Queensland. Of course, in a territory of such large extent there are
many varieties of climate, and the heat is greater along the coast
than on the elevated lands of the interior. In the northern parts of
the colony the high temperature is very trying to persons of European
descent. The mean temperature at Brisbane, during December, January
and February, is about 76 deg., while during the months of June, July
and August it averages about 60 deg. Brisbane, however, is situated
near the extreme southern end of the colony, and its average
temperature is considerably less than that of many of the towns
farther north. Thus the winter in Rockhampton averages nearly 65 deg.,
while the summer heat rises almost to 85 deg.; and at Townsville and
Normanton the average temperature is still higher. The average
rainfall along the coast is high, especially in the north, where it
ranges from 60 to 70 in. per annum, and along a strip of country south
from Cape Melville to Rockingham Bay the average rainfall exceeds 70
in. At Brisbane the rainfall is about 50 in., taking an average of
forty years. A large area of the interior is watered to the extent of
20 to 30 in. per annum, but in the west and south, more remote than
from 250 to 300 m., there is a rainfall of less than 20 in.
New South Wales.
Climatically, New South Wales is divided into three marked divisions.
The coastal region has an average summer temperature ranging from 78
deg. in the north to 67 deg. in the south, with a winter temperature
of from 59 deg. to 52 deg. Taking the district generally, the
difference between the mean summer and mean winter temperatures may be
set down as averaging not more than 20 deg., a range smaller than is
found in most other parts of the world. Sydney, situated in latitude
33 deg. 51' S., has a mean temperature of 62.9 deg. Fahr., which
corresponds with that of Barcelona in Spain and of Toulon in France,
the former of these being in latitude 41 deg. 22' N. and the latter in
43 deg. 7' N. At Sydney the mean summer temperature is 70.8 deg.
Fahr., and that of winter 53.9 deg. The range is thus 16.9 deg. Fahr.
At Naples, where the mean temperature for the year is about the same
as at Sydney, the summer temperature reaches a mean of 74.4 deg., and
the mean of winter is 47.6 deg., with a range 26.8 deg. The mean
temperature of Sydney for a long series of years was spring 62 deg.,
summer 71 deg., autumn 64 deg., winter 54 deg.
Passing from the coast to the tableland, a distinct climatic region is
entered. Cooma, with a mean summer temperature of 65.4 deg., and a
mean winter temperature of 41.4 deg., may be taken as illustrative of
the climate of the southern tableland, and Armidale of the northern.
The yearly average temperature of the latter is scarcely 65.5 deg.,
while the summer only reaches 67.7 deg., and the winter falls to 44.4
deg.
The climatic conditions of the western districts of the state are
entirely different from those of the other two regions. The summer is
hot, but on the whole the climate is very healthy. The town of Bourke,
lying on the upper Darling, may be taken as an example of many of the
interior districts, and illustrates peculiarly well the defects as
well as the excellencies of the climate of the whole region. Bourke
has exactly the same latitude as Cairo, yet its mean summer
temperature is 1.3 deg. less, and its mean annual temperature 4 deg.
less than that of the Egyptian city. New Orleans, also on the same
parallel, is 4 deg. hotter in summer. As regards winter temperature
Bourke leaves little to be desired. The mean winter reading of the
thermometer is 54.7, and accompanied as this is by clear skies and an
absence of snow, the season is both pleasant and invigorating. The
rainfall of New South Wales ranges from an annual average of 64 in. at
various points on the northern coast, and at Kiandra in the Monaro
district, to 9 in. at Milparinka in the trans-Darling district. The
coastal districts average about 42 in. per annum, the tablelands 32
in., and the western interior has an average as low as 20 in. At
Sydney, the average rainfall, since observations were commenced, has
been 50 in.
Victoria.
The climate of Victoria does not differ greatly from that of New South
Wales. The heat, however, is generally less intense in summer, and the
cold greater in winter. Melbourne, which stands in latitude 37 deg.
50' S., has a mean temperature of 57.3 deg., and therefore corresponds
with Washington in the United States, Madrid, Lisbon and Messina. The
difference between summer and winter is, however, less at Melbourne
than at any of the places mentioned, the result of a long series of
observations being spring 57 deg., summer 65.3 deg., autumn 58.7 deg.,
and winter 49.2 deg. The highest recorded temperature in the shade at
Melbourne is 110.7 deg., and the lowest 27 deg., but it is rare for
the summer heat to exceed 85 deg., or for the winter temperature in
the daytime to fall below 40 deg. Ballarat, the second city of
Victoria, lies above 100 m. west from Melbourne at a height of 1400
ft. above sea-level. It has a minimum temperature of 29 deg., and a
maximum of 104.5 deg., the average yearly mean being 54.1 deg. The
rainfall of Melbourne averages 25.58 in., the mean number of rainy
days being 131.
South Australia.
South Australia proper extends over 26 degrees of latitude, and
naturally presents considerable variations of climate. The coldest
months are June, July and August, during which the temperature is very
agreeable, averaging 53.6 deg., 51.7 deg., and 54 deg. in those months
respectively. On the plains slight frosts occur occasionally, and ice
is sometimes seen on the highlands. In summer the sun has great
power, and the temperature reaches 100 deg. in the shade, with hot
winds blowing from the interior. The weather on the whole is
remarkably dry. At Adelaide there are on an average 120 rainy days per
annum, with a mean rainfall of 20-88 in. The country is naturally very
healthful, as evidence of which may be mentioned that no great
epidemic has ever visited the state.
Western Australia.
Western Australia has practically only two seasons, the winter or wet
season, which commences in April and ends in October, and the summer
or dry season, which comprises the remainder of the Year. During the
wet season frequent and heavy rains fall, and thunderstorms, with
sharp showers, occur in the summer, especially on the north-west
coast, which is sometimes visited by hurricanes of great violence. In
the southern and early-settled parts of the state the mean temperature
is about 64 deg., but in the more northern portions the heat is
excessive, though the dryness of the atmosphere makes it preferable to
moist tropical climates. The average rainfall at Perth is 33 in. per
annum.
The climate of the Northern Territory is extremely not, except on the
elevated tablelands; altogether, the temperature of this part of the
continent is very similar to that of northern Queensland, and the
climate is not favourable to Europeans. The rainfall in the extreme
north, especially in January and February, is very heavy, and the
annual average along the coast is about 63 in. The whole of the
peninsula north of 15 deg. S. has a rainfall considerably exceeding 40
in. This region is backed by a belt of about 100 m. wide, in which the
rainfall is from 30 to 40 in., from which inwards the rainfall
gradually declines until between Central Mount Stuart and Macdonnell
ranges it falls to between 5 and 10 in.
_Fauna and Flora._--The origin of the fauna and flora of Australia has
attracted considerable attention. Much accumulated evidence, biological
and geological, has pointed to a southern extension of India, an eastern
extension of South Africa, and a western extension of Australia into the
Indian Ocean. The comparative richness of proteaceous plants in Western
Australia and South Africa first suggested a common source for these
primitive types. Dr H.O. Forbes drew attention to a certain community
amongst birds and other vertebrates, invertebrates, and amongst plants,
on all the lands stretching towards the south pole. A theory was
therefore propounded that these known types were all derived from a
continent which has been named Antarctica. The supposed continent
extended across the south pole, practically joining Australia and South
America. Just as we have evidence of a former mild climate in the arctic
regions, so a similar mild climate has been postulated for Antarctica.
Modern naturalists consider that many of the problems of Australia's
remarkable fauna and flora can be best explained by the following
hypothesis:--The region now covered by the antarctic ice-cap was in
early Tertiary times favoured by a mild climate; here lay an antarctic
continent or archipelago. From an area corresponding to what is now
South America there entered a fauna and flora, which, after undergoing
modification, passed by way of Tasmania to Australia. These immigrants
then developed, with some exceptions, into the present Australian flora
and fauna. This theory has advanced from the position of a disparaged
heresy to acceptance by leading thinkers. The discovery as fossil, in
South America, of primitive or ancestral forms of marsupials has given
it much support. One of these, _Prothylacinus_, is regarded as the
forerunner of the marsupial wolf of Tasmania. An interesting link
between divergent marsupial families, still living in Ecuador, the
_Coenolestes_, is another discovery of recent years. On the Australian
side the fact that Tasmania is richest in marsupial types indicates the
gate by which they entered. It is not to be supposed that this antarctic
element, to which Professor Tate has applied the name _Euronotian_,
entered a desert barren of all life. Previous to its arrival Australia
doubtless possessed considerable vegetation and a scanty fauna, chiefly
invertebrate. At a comparatively recent date Australia received its
third and newest constituent. The islands of Torres Strait have been
shown to be the denuded remnant of a former extension of Cape York
peninsula in North Queensland. Previous to the existence of the strait,
and across its site, there poured into Australia a wealth of Papuan
forms. Along the Pacific slope of the Queensland Cordillera these found
in soil and climate a congenial home. Among the plants the wild banana,
pepper, orange and mangosteen, rhododendron, epiphytic orchids and the
palm; among mammals the bats and rats; among birds the cassowary and
rifle birds; and among reptiles the crocodile and tree snakes,
characterize this element. The numerous facts, geological, geographical
and biological, which when linked together lend great support to this
theory, have been well worked out in Australia by Mr Charles Hedley of
the Australian Museum, Sydney.
Fauna.
The zoology of Australia and Tasmania presents a very conspicuous
point of difference from that of other regions of the globe, in the
prevalence of non-placental mammalia. The vast majority of the
mammalia are provided with an organ in the uterus, by which, before
the birth of their young, a vascular connexion is maintained between
the embryo and the parent animal. There are two orders, the
Marsupialia and the Monotremata, which do not possess this organ; both
these are found in Australia, to which region indeed they are not
absolutely confined.
The geographical limits of the marsupials are very interesting. The
opossums of America are marsupials, though not showing anomalies as
great as kangaroos and bandicoots (in their feet), and _Myrmecobius_
(in the number of teeth). Except the opossums, no single living
marsupial is known outside the Australian zoological region. The forms
of life characteristic of India and the Malay peninsula come down to
the island of Bali. Bali is separated from Lombok by a strait not more
than 15 m. wide. Yet this narrow belt of water is the boundary line
between the Australasian and the Indian regions. The zoological
boundary passing through the Bali Strait is called "Wallace's line,"
after the eminent naturalist who was its discoverer. He showed that
not only as regards beasts, but also as regards birds, these regions
are thus sharply limited. Australia, he pointed out, has no
woodpeckers and no pheasants, which are widely-spread Indian birds.
Instead of these it has mound-making turkeys, honey-suckers, cockatoos
and brush-tongued lories, all of which are found nowhere else in the
world.
The marsupials constitute two-thirds of all the Australian species of
mammals. It is the well-known peculiarity of this order that the
female has a pouch or fold of skin upon her abdomen, in which she can
place the young for suckling within reach of her teats. The opossum of
America is the only species out of Australasia which is thus provided.
Australia is inhabited by at least 110 different species of
marsupials, which is about two-thirds of the known species; these have
been arranged in five tribes, according to the food they eat, viz.,
the grass-eaters (kangaroos), the root-eaters (wombats), the
insect-eaters (bandicoots), the flesh-eaters (native cats and rats),
and the fruit-eaters (phalangers).
The kangaroo (_Macropus_) lives in droves in the open grassy plains.
Several smaller forms of the same general appearance are known as
wallabies, and are common everywhere. The kangaroo and most of its
congeners show an extraordinary disproportion of the hind limbs to the
fore part of the body. The rock wallabies again have short tarsi of
the hind legs, with a long pliable tail for climbing, like that of the
tree kangaroo of New Guinea, or that of the jerboa. Of the larger
kangaroos, which attain a weight of 200 lb. and more, eight species
are named, only one of which is found in Western Australia. Fossil
bones of extinct kangaroo species are met with; these kangaroos must
have been of enormous size, twice or thrice that of any species now
living.
There are some twenty smaller species in Australia and Tasmania,
besides the rock wallabies and the hare kangaroos; these last are
wonderfully swift, making clear jumps 8 or 10 ft. high. Other
terrestrial marsupials are the wombat (_Phascolomys_), a large,
clumsy, burrowing animal, not unlike a pig, which attains a weight of
from 60 to 100 lb.; the bandicoot (_Perameles_), a rat-like creature
whose depredations annoy the agriculturist; the native cat
(_Dasyurus_), noted robber of the poultry yard; the Tasmanian wolf
(_Thylacinus_), which preys on large game; and the recently discovered
_Notoryctes_, a small animal which burrows like a mole in the desert
of the interior. Arboreal species include the well-known opossums
(_Phalanger_); the extraordinary tree-kangaroo of the Queensland
tropics; the flying squirrel, which expands a membrane between the
legs and arms, and by its aid makes long sailing jumps from tree to
tree; and the native bear (_Phascolarctos_), an animal with no
affinities to the bear, and having a long soft fur and no tail.
The _Myrmecobius_ of Western Australia is a bushy-tailed ant-eater
about the size of a squirrel, and from its lineage and structure of
more than passing interest. It is, Mivart remarks, a survival of a
very ancient state of things. It had ancestors in a flourishing
condition during the Secondary epoch. Its congeners even then lived in
England, as is proved by the fact that their relics have been found in
the Stonesfield oolitic rocks, the deposition of which is separated
from that which gave rise to the Paris Tertiary strata by an abyss of
past time which we cannot venture to express even in thousands of
years.
We pass on to the other curious order of non-placental mammals, that
of the Monotremata, so called from the structure of their organs of
evacuation with a single orifice, as in birds. Their abdominal bones
are like those of the marsupials; and they are furnished with pouches
for their young, but have no teats, the milk being distilled into
their pouches from the mammary glands. Australia and Tasmania possess
two animals of this order--the echidna, or spiny ant-eater (hairy in
Tasmania), and the _Platypus anatinus_, the duckbilled water mole,
otherwise named the _Ornithorhynchus paradoxus_. This odd animal is
provided with a bill or beak, which is not, like that of a bird,
affixed to the skeleton, but is merely attached to the skin and
muscles.
Australia has no apes, monkeys or baboons, and no ruminant beasts. The
comparatively few indigenous placental mammals, besides the dingo or
wild dog--which, however, may have come from the islands north of this
continent--are of the bat tribe and of the rodent or rat tribe. There
are four species of large fruit-eating bats, called flying foxes,
twenty of insect-eating bats, above twenty of land-rats, and five of
water-rats. The sea produces three different seals, which often ascend
rivers from the coast, and can live in lagoons of fresh water; many
cetaceans, besides the "right whale" and sperm whale; and the dugong,
found on the northern shores, which yields a valuable medicinal oil.
The birds of Australia in their number and variety of species may be
deemed some compensation for its poverty of mammals; yet it will not
stand comparison in this respect with regions of Africa and South
America in the same latitudes. The black swan was thought remarkable
when discovered, as belying an old Latin proverb. There is also a
white eagle. The vulture is wanting. Sixty species of parrots, some of
them very handsome, are found in Australia. The emu corresponds with
the African and Arabian ostrich, the rhea of South America, and the
cassowary of the Moluccas and New Guinea. In New Zealand this group is
represented by the apteryx, as it formerly was by the gigantic moa,
the remains of which have been found likewise in Queensland. The
graceful _Menura superba_, or lyre-bird, with its tail feathers spread
in the shape of a lyre, is a very characteristic form. The
mound-raising megapodes, the bower-building satin-birds, and several
others, display peculiar habits. The honey-eaters present a great
diversity of plumage. There are also many kinds of game birds,
pigeons, ducks, geese, plovers and quails. The ornithology of New
South Wales and Queensland is more varied and interesting than that of
the other provinces.
As for reptiles, Australia has a few tortoises, all of one family, and
not of great size. The "leathery turtle," which is herbivorous, and
yields abundance of oil, has been caught at sea off the Illawarra
coast so large as 9 ft. in length. The saurians or lizards are
numerous, chiefly on dry sandy or rocky ground in the tropical region.
The great crocodile of Queensland has been known to attain a length of
30 ft.; there is a smaller one about 6 ft. in length to be met with in
the shallow lagoons of the interior of the Northern Territory. Lizards
occur in great profusion and variety. The monitor, or fork-tongued
lizard, which burrows in the earth, climbs and swims, is said to grow
to a length of 8 to 9 ft. This species and many others do not extend
to Tasmania. The monitor is popularly known as the goanna, a name
derived from the iguana, an entirely different animal. There are about
twenty kinds of night-lizards, and many which hibernate. One species
can utter a cry when pained or alarmed, and the tall-standing frilled
lizard can lift its forelegs, and squat or hop like a kangaroo. There
is also the _Moloch horridus_ of South and Western Australia, covered
with tubercles bearing large spines, which give it a very strange
aspect. This and some other lizards have power to change their colour,
not only from light to dark, but over some portions of their bodies,
from yellow to grey or red. Frogs of many kinds are plentiful, the
brilliant green frogs being especially conspicuous and noisy.
Australia is rich in snakes, and has more than a hundred different
kinds. Most of these are venomous, but all are not equally dreaded.
Five rather common species are certainly deadly--the death adder, the
brown, the black, the superb and the tiger snakes. During the colder
months these reptiles remain in a torpid state. No certain cure has
been or is likely to be discovered for their poison, but in less
serious cases strychnine has been used with advantage. In tropical
waters a sea snake is found, which, though very poisonous, rarely
bites. Among the inoffensive species are counted the graceful green
"tree snake," which pursues frogs, birds and lizards to the topmost
branches of the forest; also several species of pythons, the commonest
of which is known as the carpet snake. These great reptiles may attain
a length of 10 ft.; they feed on small animals which they crush to
death in their folds.
The Australian seas are inhabited by many fishes of the same genera as
exist in the southern parts of Asia and Africa. Of those peculiar to
Australian waters may be mentioned the arripis, represented by what is
called among the colonists a salmon trout. A very fine freshwater fish
is the Murray cod, which sometimes weighs 100 lb.; and the golden
perch, found in the same river, has rare beauty of colour. Among the
sea fish, the schnapper is of great value as an article of food, and
its weight comes up to 50 lb. This is the _Pagrus unicolor_, of the
family of _Sparidae_, which includes also the bream. Its colours are
beautiful, pink and red with a silvery gloss; but the male as it grows
old takes on a singular deformity of the head, with a swelling in the
shape of a monstrous human-like nose. These fish frequent rocky shoals
off the eastern coast and are caught in numbers outside Port Jackson
for the Sydney market. Two species of mackerel, differing somewhat
from the European species, are also caught on the coasts. The
so-called red garnet, a pretty fish, with hues of carmine and blue
stripes on its head, is much esteemed for the table. The _Trigla
polyommata_, or flying garnet, is a greater beauty, with its body of
crimson and silver, and its large pectoral fins, spread like wings, of
a rich green, bordered with purple, and relieved by a black and white
spot. Whiting, mullet, gar-fish, rock cod and many others known by
local names, are in the lists of edible fishes belonging to New South
Wales and Victoria. Oysters abound on the eastern coast, and on the
shelving banks of a vast extent of the northern coast the pearl oyster
is the source of a considerable industry.
Two existing fishes may be mentioned as ranking in interest with the
_Myrmecobius_ (ant-eater) in the eyes of the naturalist. These are the
_Ceratodus Forsteri_ and the Port Jackson shark. The "mud-fish" of
Queensland (_Ceratodus Forsteri_) belongs to an ancient order of
fishes--the Dipnoi, only a few species of which have survived from
past geological periods. The Dipnoi show a distinct transition between
fishes and amphibia. So far the mud-fish has been found only in the
Mary and the Burnett rivers. Hardly of less scientific interest is the
Port Jackson shark (_Heterodontus_). It is a harmless helmeted
ground-shark, living on molluscs, and almost the sole survivor of a
genus abundant in the Secondary rocks of Europe.
Flora.
The eastern parts of Australia are very much richer both in their
botany and in their zoology than any of the other parts. This is due
in part to the different physical conditions there prevailing and in
part to the invasion of the north-eastern portion of the continent by
a number of plants characteristically Melanesian. This element was
introduced via Torres Strait, and spread down the Queensland coast to
portions of the New South Wales littoral, and also round the Gulf of
Carpentaria, but has never been able to obtain a hold in the more arid
interior. It has so completely obliterated the original flora, that a
Queensland coast jungle is almost an exact replication of what may be
seen on the opposite shores of the straits, in New Guinea. This wealth
of plant life is confined to the littoral and the coastal valleys, but
the central valleys and the plateaux have, if not a varied flora, a
considerable wealth of timber trees in every way superior to the flora
inland in the same latitudes. In the interior there is little change
in the general aspect of the vegetation, from the Australian Bight to
the region of Carpentaria, where the exotic element begins. Behind the
luxuriant jungles of the sub-tropical coast, once over the main range,
we find the purely Australian flora with its apparent sameness and
sombre dulness. Physical surroundings rather than latitude determine
the character of the flora. The contour lines showing the heights
above sea-level are the directions along which species spread to form
zones. Putting aside the exotic vegetation of the north and east
coast-line, the Australian bush gains its peculiar character from the
prevalence of the so-called gum-trees (_Eucalyptus_) and the acacias,
of which last there are 300 species, but the eucalypts above all are
everywhere. Dwarfed eucalypts fringe the tree-limit on Mount
Kosciusco, and the soakages in the parched interior are indicated by a
line of the same trees, stunted and straggling. Over the vast
continent from Wilson's Promontory to Cape York, north, south, east
and west--where anything can grow--there will be found a gum-tree. The
eucalypts are remarkable for the oil secreted in their leaves, and the
large quantity of astringent resin of their bark. This resinous
exudation (Kino) somewhat resembles gum, hence the name "gum" tree. It
will not dissolve in water as gums do, but it is soluble in alcohol,
as resin usually is. Many of the gum-trees throw off their bark, so
that it hangs in long dry strips from the trunk and branches, a
feature familiar in "bush" pictures. The bark, resin and "oils" of the
eucalyptus are well known as commercial products. As early as 1866,
tannic acid, gallic acid, wood spirit, acetic acid, essential oil and
eucalyptol were produced from various species of eucalyptus, and
researches made by Australian chemists, notably by Messrs. Baker and
Smith of the Sydney Technical College, have brought to light many
other valuable products likely to prove of commercial value. The genus
_Eucalyptus_ numbers more than 150 species, and provides some of the
most durable timbers known. The iron-bark of the eastern coast uplands
is well known (_Eucalyptus sideroxylon_), and is so called from the
hardness of the wood, the bark not being remarkable except for its
rugged and blackened aspect. Samples of this timber have been studied
after forty-three years' immersion in sea-water. Portions most liable
to destruction, those parts between the tide marks, were found
perfectly sound, and showed no signs of the ravages of marine
organisms. Other valuable timber trees of the eastern portion of the
continent are the blackbutt, tallow-wood, spotted gum, red gum,
mahogany, and blue gum, eucalyptus; and the turpentine (_Syncarpia
laurifolia_), which has proved to be more resistant to the attacks of
teredo than any other timber and is largely used in wharf construction
in infested waters. There are also several extremely valuable soft
timbers, the principal being red cedar (_Cedrela Toona_), silky oak
(_Grevillea robusta_), beech and a variety of teak, with several
important species of pine. The red gum forests of the Murray valley
and the pine forests bordering the Great Plains are important and
valuable. In Western Australia there are extensive forests of
hardwood, principally jarrah (_Eucalyptus marginata_), a very durable
timber; 14,000 sq. m. of country are covered with this species. Jarrah
timber is nearly impervious to the attacks of the teredo, and there is
good evidence to show that, exposed to wear and weather, or placed
under the soil, or used as submarine piles, the wood remained intact
after nearly fifty years' trial. The following figures show the high
density of Australian timber:--
Australian Specific
timber. gravity.
Jarrah 1.12
Grey iron-bark 1.18
Red iron-bark 1.22
Forest oak 1.21
Tallow wood 1.23
Mahogany 1.20
Grey gum .917
Red gum .995
European Specific
timber. gravity.
Ash .753
Beech .690
Chestnut .535
British oak .99
The resistance to breaking or rupture of Australian timber is very
high; grey iron-bark with a specific gravity of 1.18 has a modulus of
rupture of 17,900 lb. per sq. in. compared with 11,800 lb. for British
oak with a specific gravity of .69 to .99. No Australian timber in the
foregoing list has a less modulus than 13,100 lb. per sq. in.
Various "scrubs" characterize the interior, differing very widely from
the coastal scrubs. "Mallee" scrub occupies large tracts of South
Australia and Victoria, covering probably an extent of 16,000 sq. m.
The mallee is a species of eucalyptus growing 12 to 14 ft. high. The
tree breaks into thin stems close to the ground, and these branch
again and again, the leaves being developed umbrella-fashion on the
outer branches. The mallee scrub appears like a forest of dried osier,
growing so close that it is not always easy to ride through it. Hardly
a leaf is visible to the height of one's head; but above, a crown of
thick leather-like leaves shuts out the sunlight. The ground below is
perfectly bare, and there is no water. Nothing could add to the
sterility and the monotony of these mallee scrubs. "Mulga" scrub is a
somewhat similar thicket, covering large areas. The tree in this
instance is one of the acacias, a genus distributed through all parts
of the continent. Some species have rather elegant blossoms, known to
the settlers as "wattle." They serve admirably to break the sombre and
monotonous aspect of the Australian vegetation. Two species of acacia
are remarkable for the delicate and violet-like perfume of their
wood--myall and yarran. The majority of the species of _Acacia_ are
edible and serve as reserve fodder for sheep and cattle. In the
alluvial portions of the interior salsolaceous plants--saltbush,
bluebush, cottonbush--are invaluable to the pastoralist, and to their
presence the pre-eminence of Australia as a wool-producing country is
largely due.
Grasses and herbage in great variety constitute the most valuable
element of Australian flora from the commercial point of view. The
herbage for the most part grows with marvellous rapidity after a
spring or autumn shower and forms a natural shelter for the more
stable growth of nutritious grasses.
Under the system of grazing practised throughout Australia it is
customary to allow sheep, cattle and horses to run at large all the
year round within enormous enclosures and to depend entirely upon the
natural growth of grass for their subsistence. Proteaceous plants,
although not exclusively Australian, are exceedingly characteristic of
Australian scenery, and are counted amongst the oldest flowering
plants of the world. The order is easily distinguished by the hard,
dry, woody texture of the leaves and the dehiscent fruits. They are
found in New Zealand and also in New Caledonia, their greatest
developments being on the south-west of the Australian continent.
Proteaceae are found also in Tierra del Fuego and Chile. They are also
abundant in South Africa, where the order forms the most conspicuous
feature of vegetation. The range in species is very limited, no one
being common to eastern and western Australia. The chief genera are
banksia (_honeysuckle_), and hakea (_needle bush_).
The Moreton Bay pine (_Araucaria Cunninghamii_) is reckoned amongst
the giants of the forest. The genus is associated with one long
extinct in Europe. Moreton Bay pine is chiefly known by the utility of
its wood. Another species, _A. Bidwillii_, or the bunya-bunya,
afforded food in its nut-like seeds to the aborigines. A most
remarkable form of vegetation in the north-west is the gouty-stemmed
tree (_Adansonia Gregorii_), one of the Malvaceae. It is related
closely to the famous baobab of tropical Africa. The "grass-tree"
(_Xanthorrhoea_), of the uplands and coast regions, is peculiarly
Australian in its aspect. It is seen as a clump of wire-like leaves, a
few feet in diameter, surrounding a stem, hardly thicker than a
walking-stick, rising to a height of 10 or 12 ft. This terminates in a
long spike thickly studded with white blossoms. The grass-tree gives
as distinct a character to an Australian picture as the agave and
cactus do to the Mexican landscape. With these might be associated the
gigantic lily of Queensland (_Nymphaea gigantea_), the leaves of which
float on water, and are quite 18 in. across. There is also a gigantic
lily (_Doryanthes excelsa_) which grows to a height of 15 feet. The
"flame tree" is a most conspicuous feature of an Illawarra landscape,
the largest racemes of crimson red suggesting the name. The waratah or
native tulip, the magnificent flowering head of which, with the
kangaroo, is symbolic of the country, is one of the Proteaceae. The
natives were accustomed to suck its tubular flowers for the honey they
contained. The "nardoo" seed, on which the aborigines sometimes
contrived to exist, is a creeping plant, growing plentifully in swamps
and shallow pools, and belongs to the natural order of Marsileaceae.
The spore-cases remain after the plant is dried up and withered. These
are collected by the natives, and are known over most of the continent
as nardoo.
No speculation of hypothesis has been propounded to account
satisfactorily for the origin of the Australian flora. As a step
towards such hypothesis it has been noted that the Antarctic, the
South African, and the Australian floras have many types in common.
There is also to a limited extent a European element present. One
thing is certain, that there is in Australia a flora that is a remnant
of a vegetation once widely distributed. Heer has described such
Australian genera as Banksia, Eucalyptus, _Grevillea_ and _Hakea_ from
the Miocene of Switzerland. Another point agreed upon is that the
Australian flora is one of vast antiquity. There are genera so far
removed from every living genus that many connecting links must have
become extinct. The region extending round the south-western extremity
of the continent has a peculiarly characteristic assemblage of typical
Australian forms, notably a great abundance of the Proteaceae. This
flora, isolated by arid country from the rest of the continent, has
evidently derived its plant life from an outside source, probably from
lands no longer existing.