between the Wooramel and Minilya rivers. The upper and terrestrial
type of the Carboniferous include sandstones with Stigmaria and
Lepidodendron in the Kimberley district, and the coals of the Irwin
coalfield, the age of which is proved by the interstratification of the
coal seams with beds containing Productus subquadratus, Cyrtina
carbonaria and Aviculopecten subquinquelineatus. The Mesozoic
rocks were discovered in 1861, and their chief outcrop is along the
western coast plains of Westralia between Geraldton and Perth.
They have been pierced by many bores put down for artesian wells.
The fossils indicate a Lower Jurassic age; and, according to Etheridge,
some of the fossils are Lower Cretaceous. The Collie coalfield, to
the east of Bunbury, is generally regarded as Mesozoic. Its coal is
inferior in quality to that of Eastern Australia, and contains on an
average of 34 analyses 11·77% of moisture, and 8·62% of
ash. According to Etheridge its age is Permo-Carboniferous. The
Kainozoic rocks include the marine limestones in the Nullarbor
Plains at the head of the Great Australian Bight, whence they
extend inland for 150 m. They have no surface water, but the rainfall
in this district nourishes artesian wells.
The occurrence of marine Kainozoic beds under the western coastal plain is proved
by the bores, as at Carnarvon, where they appear to be over 1000 ft.
in thickness. The coastal region also includes sheets of clay and
sandstone, with deposits of brown coal as on the Fitzgerald river
on the southern coast, and in the basin of the Gascoyne. The
Archean plateau of the interior is covered by wide sheets of sub aerial
and lacustrine deposits, which have accumulated in the basins
and river valleys. They include mottled clays, lateritic ironstones
and conglomerates. In places the materials have been roughly
assorted by river action, as in the deep lead of Kanowna. The clays
contain the bones of the Diprotodon, so that they are probably of
Upper Pliocene or Pleistocene age. The Kainozoic volcanic period
of Australia is represented by the basalts of Bunbury and Black
Point, east of Flinders Bay.
A bibliography of Westralian geology has been issued by Maitland, Bulletin Geol. Survey, No. 1, 1898. An excellent summary of the mineral wealth of the state has been given by Maitland, Bulletin 8, No. 4, 1900, pp. 7-23, also issued in the Year-book of Western Australia. The main literature of the geology of Westralia is in the Bulletins of the Geol. Survey, and in the reports of the Mines Department. A general account of the gold-mining has been given by A. G. Charleton, 1902; and also by Donald Clark, Australian Mining and Metallurgy (1904). (J. W. G.)
Flora.— Judged by its vegetable forms, Western Australia would seem to be older than eastern Australia, South Australia being of intermediate age. Indian relations appear on the northern side, and South African on the western. There are fewer Antarctic and Polynesian representatives than in the eastern colonies. European forms are extremely scarce. Compared with the other side of Australia, a third of the genera on the south-west is almost wanting in the south-east. In the latter, 55, having more than ten species each, have 1260 species; but the former has as many in 55 of its 80 genera. Of those 55, 36 are wanting in the south-east, and 17 are absolutely peculiar. There are fewer natural orders and genera westward, but more species. Baron von Müller declared that “nearly half of the whole vegetation of the Australian continent has been traced to within the boundaries of the Western Australian territory.” He includes 9 Malvaceae, 6 Euphorbiaceae, 2 Rubiaceae, 9 Proteaceae, 47 Leguminosae, 10 Myrtaceae, 12 Compositae, 5 Labiatae, 6 Cyperaceae, 13 Convolvulaceae, 16 Gramineae, 3 Filices, 10 Amaranthaceae. Yet over 500 of its tropical species are identified with those of India or Indian islands. While seven tenths of the orders reach their maximum south-west, three-tenths do so south-east. Cypress pines abound in the north, and ordinary pines in Rottnest Island. Sandalwood (Santalum cygnorum) is exported. The gouty stem baobab (Adansonia) is in the tropics. Xanthorrhoea, the grass tree, abounds in sandy districts. Mangrove bark yields a purple tan. Palms and zamias begin in the north-west. The Melaleuca Leucadendron is the paperbark tree of settlers. The rigid-leafed Banksia is known as the honeysuckle. Casuarinae are the he and she oaks of colonists, and the Exocarpus is their cherry tree. Beautiful flowering shrubs distinguish the south-west; and the deserts are all ablaze with flowers after a fall of rain. Poison plants are generally showy Leguminosae, Sida and the Gastrolobium.
The timber trees of the south-west are almost unequalled. Of the Eucalypts, the jarrah or mahogany, E. marginalia, is first for value. It runs over five degrees of latitude, and its wood resists the teredo and the ant. Sir Malcolm Fraser assigns 14,000 sq. m. to the jarrah, 10,000 to E. viminalis, 2300 to the karri (E. colossea or E. diversicolor), 2400 to York gum (E. loxophleba), 800 to the red gum (E. calophylla) and 500 to tuart or native pear (E. gomphocephala). Not much good wood is got within 20 m. of the coast. The coachbuilder’s coorup rises over 300 ft. Morrel furnishes good timber and rich oil. An ever-increasing trade is done in the timber of the south-western forests.
Fauna.—Among the mammals are the Macropus giganteus, M. irma, M. dama, M. brachyurus, Lagorchestes fasciatus, Beltongia penicillata, Phalangista vulpecula, Pseudochirus cooki, Dasyurus geoffroyi, Tarsipes rostratus, Antechinus apicalis, Perameles obesula, Perameles myosurus, Myrmecobius fasciatus. Fossil forms partake of the existing marsupial character, Diprotodon being allied to the wombat and kangaroo. Nail-bearing kangaroos are in the north-west; the banded one, size of a rabbit, is on Shark’s Bay. Nocturnal phalangers live in holes of trees or in the ground. Carnivorous Phascogalae are found in south-west. There are three kinds of wombat. The rock-loving marsupial Osphranter is only in the north-east, and Perameles bougainvillea at Shark’s Bay. The dalgyte or Petrogale lagotis is at Swan river and Hypsiprymnus in the south. The colony has only two species of wallabies to five in New South Wales. The Halmaturus of the Abrolhos is a sort of wallaby; a very elegant species is 18 in. long. The pretty Dromicia, 6 in. long, lives on stamens and nectar, like the Tarsipes, having a brush at the tip of its tongue; its tail is prehensile. The hare-like Lagorchestes fasciatus is a great leaper. The Hapalolis of the interior has nests in trees. Beaver rats and other small rodents are troublesome, and bats are numerous. The dingo is the wild dog. The platypus (Ornithorhynchus) and the Echidna are the only forms of the Monotremata. The seal, whale and dugong occur in the adjacent seas.
The west is not so rich as the east of Australia in birds. Many forms are absent and others but poorly represented, though some are peculiar to the west. The timbered south-west has the greatest variety of birds, which are scarce enough in the dry and treeless interior. Of lizards the west has 12 genera not found in eastern Australia. Of snakes there are but 15 species to 3 in Tasmania and 31 in New South Wales. While the poisonous sorts are 2 to 1 in the east, they are 3 to 1 in the west. The turtle is obtained as an article of food. The freshwater fishes are not all like those of the east. They include the mullet, snapper, ring fish, guard fish, bonita, rock cod, shark, saw fish, parrot fish and cobbler. Under the head of fisheries may be mentioned the pearl oyster, which is dived for by natives at Shark’s Bay; the trepang or beche-de-mer is also met with in the north. Insects are well represented, especially Coleoptera, Lepidoptera, Hymenoptera, Hemiptera and Diptera.
Climate.— With little or no cold anywhere, the heat of summer over the whole area is considerable. Western Australia differs from the country to the east in having no extensive ranges to collect vapour, while the trade winds blow off the dry land instead of from the ocean; for these two reasons the climate is very dry. Thunderstorms often supply almost the only rainfall in the interior. The south-western corner, the seat of settlements, is the only portion where rains can be depended on for cultivation; but even there few places have a rainfall of 40 in. As one goes northward the moisture lessens. The north-west and all the coast along to Kimberley, with most of that district, suffer much from dryness. The north-east comes in summer within the sphere of the north-west monsoons, though just over the low coast-range few showers are known. The south coast, exposed to polar breezes, with uninterrupted sea, has to endure lengthened droughts. In the Swan river quarter the rainfall is in winter, being brought by north-west winds, and summer days have little moisture. While the south wind cools the settled region, it comes over the parched interior to the northern lands. The hot wind of Swan river is from the east and north-east; but it is from the south in summer to Kimberley and the north-west. In one season the land breeze is hot, in another cool, but always dry.
The climate of Perth is typical of the south-western districts. There are two distinct seasons, the winter and the summer. The winter commences somewhat abruptly, being ushered in by heavy rains; it begins usually not earlier than the middle of April or later than the middle of May, and continues until towards the end of October. The winters are, as a rule, very mild, but there is some cold weather in July and August, and though there is little at the coast, frost is not uncommon inland. The summer is heralded by an occasional hot day in October, in November the weather becomes settled and continues warm until the end of March. In the four months, December to March, the maximum temperature in the shade exceeds 90° on an average on 37 days, but as a rule the heat does not last long, the evenings and nights being tempered by a cool breeze.
In the interior the climate resembles that of the south-west in regard to the occurrence of two seasons only. The winter, however, has much less rain than on the coast, and is cold, clear and bracing. The summer is, as a rule, hot, but is tempered in the south by occasional cool changes, though unrelieved as the tropic is approached. Within the tropics there are two seasons, the wet and the dry. The wet season is most unpleasant, the temperature rarely falling below 100°; the dry season, which lasts from April to November, is usually fine, clear and calm. The average rainfall at Perth is 33 in. falling on no days; the mean maximum temperature is 74·9° and the minimum 54·8°; at Coolgardie the mean maximum is 77·8° and the mean minimum 52·4°, at Wyndham, on the north-west coast, the mean maximum is 93·9° and the minimum 75·4°.
Population.—Population made very slow increase under the old conditions of settlement, and even when gold was discovered in 1882 at Kimberley, and five years later at Yilgam, no great impetus was given to the colony, and at the census of 1891 the population was still under 50,000. The sensational gold finds
