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The restless Earth

The mountains of Gariwerd sit perched upon the otherwise flat terrain of Victoria’s western plains, their peaks and valleys visible for many kilometres from every direction. Along with the hundreds of volcanoes and eruption points of the Newer Volcanics Province that extends from Melbourne west to Mount Gambier, Gariwerd is the most distinctive geological feature of western Victoria. At the highest level of description, Gariwerd is a series of mountain ranges running roughly north to south, the southern and westernmost point of Australia’s Great Dividing Range that unfolds east across Victoria before a northward journey that traces the eastern seaboard for 3700 km to Queensland. Gariwerd’s highest point is at Duwul, Mount William, in the east, and from here in each direction the ranges drop in elevation to the north and south. The geology of the ranges has determined its soils, and therefore plant and animal communities, as well as its water resources and, to an extent, its local climate.

Geology and landform

Gariwerd has a distinctly rugged and broken form, made up of sandstones, mudstones and siltstones. Steep escarpments, dropping abruptly to the plains below, line the eastern face of the ranges, while shallow, dipping slopes roll away to the west. This landform – the distinct cuesta landform – has been broken and cracked as the mountains settled and became weathered (Plate 1.1). To the west of the main ranges are Burrunj, or the Black Range, as well as further, final outcrops at Djurid (Mount Arapiles) and Grimgundidj (the Dundas Range); these are part of the same formations as Gariwerd, or what geologists came to call the Grampians Group.

The first European to attempt an account of the region’s geological form was Thomas Mitchell, Surveyor General of New South Wales. His expedition journals have provided a wealth of information on the landscape the Europeans first encountered in the middle of the nineteenth century. In 1836, Mitchell had observed that, when he and his party climbed Duwul, that ‘The surface at the summit of the cliffs was broad and consisted of large blocks of sandstone, separated by wide fissures … These rocks were inclined but slightly towards the north-west … [when] we reached the highest point [we] found that it consisted of naked sandstone … No rocks could be found near the summit to shelter us from the piercing wind and sleet’.¹ As his men continued their journey around Gariwerd, ‘proceeding over the plains extending along the interior side of the Grampians of the South’, he found that the ‘soil of such plains consisted chiefly of clay, and we had recently found that it bore the wheels of the waggons much better during the winter season than the thin and loose soil on the sides of hills; apparently because this lay on rock, or a substratum so tenacious as to support the water in or just under the surface.’²

Around the Wimmera River, he noted that ‘The richness of the soil and the verdure near the river, as well as the natural beauty of the scenery could scarcely be surpassed in any country.’³ Climbing Mura Mura, which he named Mount Zero, he described it as ‘highly micaceous sandstone; the whole being inclined towards the north-west’; from that vantage point he saw ‘a very remote, isolated hill on the low country far to the northward which I had also seen from Mount William, and from several stations on our route.’ Mitchell saw that an ‘isolated mass appeared to the westward, having near its base a most remarkable rock resembling a mitre.’ Beyond this, he wrote

the distant horizon was not quite so level as the plains of the interior usually are and, as far as I could see northward with a good telescope, I perceived open forest land and various fine sheets of water. I observed with great satisfaction that the Grampians terminated to the westward on a comparatively low country. This was an important object of attention to me then as it comprised all that intervened between us and the southern coast; in which direction I perceived only one or two groups of conical hills. I resolved however, before turning southwards, to extend our journey to the isolated mass already mentioned, which I afterwards named Mount Arapiles. After descending from Mount Zero I proceeded towards the track of the carts and found that the plains, unlike any hitherto seen, undulated so much that in one place I could perceive only the tops of trees in the hollows. On these plains I found small nodules of highly ferruginous sandstone.⁴

After climbing Djurid, which he had now named Mount Arapiles, Mitchell ‘had a good view of the Grampians of the South and, discovering that a lofty range extended from them southward, I named it the Victoria Range having also recognised and intersected Mount William’. He continued to recall how he

could see no high land to the westward, and the hill on which I stood seemed to divide the singular lacustrine [lakes] country from that where the character of the surface was fluviatile [rivers]. Mount Arapiles is a feature which may always be easily recognised both by its isolated position and by its small companion the Mitre Rock, situated midway between it and the lake to the northward, which I named Mitre Lake after the little hill, its neighbour. Like the mountains in the east Mount Arapiles consists of sandstone passing into quartz, the whole apparently an altered sandstone, the structure being in one part almost destroyed, in others perfectly distinct and containing pebbles of quartz. At the western extremity this rock occurs in columns, resembling, at a distance, those of basalt.⁵

Mitchell’s journals epitomise the early attempts by Europeans to describe and account for, in the scientific language of the day, the lands of the world they began to explore and claim for themselves. To identify and categorise, and to map and measure, was to bring more and more of the world into their domain. From the outset, almost all the geologists who came in Mitchell’s wake believed that the ranges had been formed when the surrounding landscape was weathered away, leaving behind the hulking silhouette familiar today. They were, by and large, correct in their observations but the details would take over a century to elucidate as new techniques and understandings of the Earth evolved and emerged.

The first attempt at an assessment of Gariwerd’s geology was A. R. C. Selwyn and G. H. F. Ulrich’s brief article ‘Notes on Physical Geography, Geology, and Mineralogy of Victoria’, in 1867. This was followed in 1873 by F. M. Krause’s report for the Geological Survey of Victoria, which accurately mapped and accounted for the physical form of the ranges. Although goldrushes in the early twentieth century produced utilitarian maps of promising sites around the mountains, it was not until the 1960s that a new, fully realised geological map of Gariwerd was authored by a PhD student working for the Geological Survey of Victoria. This was followed by some smaller studies. Private companies also began to take interest in the region, drilling for gold and base metals. The most detailed report on Gariwerd appeared in 1997 and acknowledges all this earlier work. It was authored by R. A. Cayley and D. H. Taylor for the Victorian Department of Natural Resources and Environment, and it is from this that we have gained a full picture of the region’s geology.⁶

Underlying the Gariwerd mountains is a layer of bedrock some 500 million years old, laid down in the Cambrian Period – material that was originally volcanic and sediment before being buried, crushed and subjected to intense temperatures over eons. This bedrock is generally covered over with more recent layers of rock and sediment throughout the region, but some kilometres to the east, outcrops of ancient volcanic and sedimentary rocks, including greenstones (andesite), chert and chalcedony, appear at the Mount Stavely Volcanic Complex, reminders of this region’s unfathomably deep past when it was still part of the ancient southern supercontinent of Gondwana.

To the east of the mountains, most of what would become Victoria was a deep ocean, its coastline running from north to south along the Gariwerd region. To the west was mountainous terrain. Perhaps 430 million years ago, in the Ordovician Period, when the first fish were appearing and plants were beginning their invasion of the land, the Earth’s surface in the region underwent violent and intense folding, lifting some areas up into hills and mountains and pushing other regions down into troughs and valleys. Not long after this, in the Silurian Period, a trough in what is now western Victoria began to fill with sediments, water-borne debris washed away from the surrounding Gondwanan landscape. Rivers drained the mountains from the west into the ocean, leaving sand and gravel behind on extensive river flats that would become the Grampians Group. As the rivers met the ocean, they sometimes formed lagoons and tidal inlets, which left behind accumulated red mud and silt. Sediment was also deposited along the shoreline, and evidence of this can be seen in the distinctive marks left upon rocks by crashing waves.

The sediments were left behind by the actions of rivers and oceans in four distinct stages. First came what geologists call the Red Man Bluff sediments, which are on average 1800 m thick. They form the Mount William Ranges, as well as the areas around Mount Zero (Mura Mura) and Mount Stapylton. Then came the Silverband Formation, 850 m of a soft, reddish sediment that is easily eroded; it has been carved away by, for example, Fyans Creek. The sediments laid down in the Silverband Formation contain fossils that speak to the ocean environment in which they were deposited: fish teeth, spines and scales for example, and a small, mollusc-like shellfish – the brachiopod – that was common in the Palaeozoic era many hundreds of millions of years ago. After the Silverband Formation was laid down, next came the Mount Difficult Subgroup—920 m of coarse sandstone that meets the Silverband sediments in a sharp junction along the Serra Range. The newest materials that form Gariwerd are the Victoria Range deposits, which consist of 2800 m of sandstone both coarse and fine, today often covered by eroded sand and scree. As the movements of the continents and tectonic plates began exerting pressure on the Grampians Group sediments, they thickened, hardened, and deformed – stronger sandstone beds pushed up, stacking up over mudstone, while other beds were thrown up on to their edges (such as at The Terraces and Golton Gorge). From about 410 million years ago, therefore, the Grampians Group had taken on their present form.

In the Devonian Period, some 350 million years ago, large masses of molten, granitic magma, called plutons, pushed up from deep within the crust of the Earth, cooling slowly as they remained trapped under layers of sedimentary rock. These plutons intruded into the Grampians Group, waiting for erosion to expose them. Further to the west, volcanic activity formed the extensive Rocklands Volcanics. Around this time, fish were the ascendant species on the planet, and algae and fungi had appeared too. Gondwana collided with the smaller supercontinent Euramerica (or Laurussia) to form Pangaea, a colossal landmass in the southern hemisphere surrounded by an ocean of unimaginable horizons called Panthalassa.

The rocks and sediments of Gariwerd that would one day come to rise above the plains were still mostly underground at the start of the Mesozoic era some 195 million years ago, when the first dinosaurs and mammals appeared. Any exposed sediments were gradually worn down over the age of the dinosaurs, during which Pangaea itself began to rift and break apart with new supercontinents, Laurasia and Gondwanaland, forming in the northern and southern hemispheres. In the early Cretaceous Period, Gariwerd still remained generally hidden under what was now a flat plain, while Gondwana itself began splitting into the continents that would become Africa, South America, India, Antarctica and Australia. In a journey that continues to this day, Australia began a lonely voyage north towards the equator, and the lush, temperate forests of Gondwana gave way to deserts and grasslands, droughts and floods.

From about 65 million years ago, at the end of the Mesozoic era, the seas began to encroach upon the land again, wearing away at the landscape surrounding Gariwerd and leaving only the quartz-heavy sandstones of the Grampians Group behind. The molten masses that had pushed up into Gariwerd and slowly cooled were exposed, themselves becoming subject to weathering and erosion. The harder, more resistant granites formed low, rounded hills in the Victoria Valley. The softer material was eroded away to form basins in the Mackenzie River and Mafeking areas. When the molten magma welled up, the surrounding rock became baked and hardened; as Gariwerd continued to be subject to the movements of the Earth, this rock was faulted, forming waterfalls along the Mackenzie. Some of the magma escaped upward through cracks and into the Mount Difficult and Mount William sandstones, forming dykes and sills, creating a grand stairway up the eastern face of Mount Rosea, and laying a path still used on the Wonderland Trail. These volcanic materials were rich in minerals, bringing the elements needed for abundant vegetation and plant growth to the surface. By the time the Mesozoic era came to an end, when the dinosaurs became extinct, marsupials and birds had appeared, as had flowering plants, ferns and cycads.

To the north of Gariwerd, the sediment that would form today’s Wimmera Plains was laid down as the sea invaded the Murray Basin from about 58 million years ago. At around 14 million years ago, the coastline – the sea also having invaded the Otway Basin to the south – lapped at the feet of Gariwerd, which was, along with the Dundas and Black Ranges, part of a southern promontory extending into the sea. Mount Arapiles stood apart as an island off the coast; platforms and crags were shaped by waves, and an ancient beach was left behind to the north. As an unusual remnant of Gariwerd’s ancient coastal past, the coast banksia (Banksia integrifolia) can be found in isolated patches high atop Mount Rosea and the Major Mitchell Plateau.⁷

Gariwerd had been formed, but its surrounding landscape would be subject to further violent upheavals. Volcanic activity across the region beginning about two million years ago would eventually form hundreds of volcanoes and eruption points in the Newer Volcanics Province, the western extent of which lies along the southern parts of the Gariwerd ranges. As volcanoes around Gariwerd erupted, patterns of drainage were disrupted as lava flows partially filled valleys, creating shallow lakes and swamps around the mountains. Lava flows from Mount Napier and Mount Eccles – which erupted around 30 000 years ago – further altered the landscape and encroached into the Victoria Valley region. Volcanic activity to the south of Gariwerd bequeathed a rolling, fertile landscape, and perhaps the richest soils of mainland Australia. In contrast, receding oceans in the north left behind a dry, infertile, and semi-arid landscape.

Climate and water

At around the same time as volcanic activity began to reshape the region – a bit over two million years ago – the Pleistocene Period began, and the global climate began a cycle of ice ages, or glacial periods, and warm, interglacial phases. As ice sheets grew and shrank over these cycles of climatic change, each lasting between 50 000 and 100 000 years, the seas rose and fell by over 100 m. When the sea was at its lowest, a great continent – Sahul – was formed as land bridges connected Tasmania and New Guinea to the mainland Australian landmass. More recently, about 70 000 years ago, the sea dropped to a level that exposed a series of islands between south-east Asia and north-west Australia. By the time the first Australians began to live in and around Gariwerd just over 20 000 years ago, its form had taken the shape we see today. Its climate and environment, however, would continue to shift and transform.

Since the end of the last ice age, Gariwerd and its surrounding plains have undergone major environmental changes. Evidence from the volcanic plains to the east – studies of water levels and salinity at Lakes Keilambete, Gnotuk and Bullenmerrie – provide insights into some of these local changes since the late Pleistocene. About 20 000 years ago, the climate of the region was generally much drier, but both temperatures and rainfall were beginning to increase. Parts of western Victoria were already swampy, but from around 10 500 years ago, at the start of the Holocene, the region became wetter, and as the wettest period of the Holocene in south-eastern Australia came to a peak, lakes on the western plains began to overflow about 7000 years ago. Then, a gradual drying out of the region followed, before a period of instability and movement between drier and wetter conditions. The region was relatively wet just before the arrival of Europeans in the late 1830s, but this was followed by a substantial and rapid fall in lake levels from the 1840s onwards.⁸

It was fateful that the Europeans would first reconnoitre the region in a period of relatively high precipitation and moisture, and therefore lush, alluring vegetation. But on the surrounding plains of Gariwerd about 20 000 years ago, conditions were colder, drier, and probably much windier, and the most common form of vegetation type in south-west Victoria was much like that of a cool semi-arid grassland or steppe. From the early Holocene, when rainfall and temperatures began to increase, a casuarina woodland began to emerge, and tree cover started to expand. Around 8000 years ago, as they were in other parts of temperate Australia, eucalypts became the dominant species in western Victoria.⁹ The Wimmera would have been in the southernmost reaches of a greatly expanded arid interior zone. Sheoak dominated in the open woodland that established itself in semi-arid conditions between 10 000 and 6600 years ago. After this, eucalypts began to spread and dense mallee scrub became the most common form of vegetation; as the climate became wetter, coniferous callitris trees – a kind of cypress – also began to spread. Some lakes in the Wimmera and Mallee regions became permanently filled but dried again about 2200 years ago with decreasing rainfall. Casuarina woodlands won out over the callitris, and mallee vegetation began to dwindle somewhat, thickening again about 800 years ago when wetter conditions returned.¹⁰

At the end of the Pleistocene the mountains stood on the threshold of the arid, sandy Australian interior. In more sheltered parts of the ranges, some woodland might have survived, meaning that the mountains might have acted as a refuge for some species, and thus would have been a more diverse environment than the surrounding plains. In general, it is likely that the mountains were mostly treeless, and the ranges were marked by low heath and scrub. Valleys between the peaks were open and grassy. From about 10 000 years ago, tree cover was certainly minimal, with perhaps some casuarina scattered through the grasslands. From this point, woodlands began to spread across the ranges as they did in other parts of western Victoria, and this rapidly emerging tree cover would have at first been dominated by casuarina species, followed by eucalypts. The red gum woodlands that the Europeans encountered in the Victoria Valley in the middle of the nineteenth century began to establish themselves around 7000 years ago.¹¹ The vast botanical reserve known to both Indigenous inhabitants and later European visitors thus emerged relatively recently.

By the time Europeans had colonised the region, the mountains were an ark of nature, an island sitting at a transition point between the cooler, wetter regions to its south and the warmer, more arid north. The ranges, running in a north–south direction as they do, lay in the path of rain-bearing westerly winds. They had, and still have, a vastly different climate from the surrounding plains. Near the southern coast of Victoria, annual rainfall sits at just over 800 mm, and steadily decreases moving into the north: at Hamilton, the average is a bit more than 600 mm per year, and at Horsham annual rainfall is just under 500 mm. In the mountains themselves, precipitation can be up to 1000 mm on average per annum.

The mountains are drained in the north and east by the Mount William, Fyans, and MacKenzie creeks, which in turn feed the Wimmera River as it journeys north to disappear in the sandy plains of northern Victoria. In heavy rains, the Wimmera will push further north into Wyperfeld National Park, some 150 km from the ranges, where shallow lakes and creek beds begin to fill and river red gums can grow. In the south and west, the mountains drain into Dwyer Creek, the Wannon River, which rises below Mount Abrupt, and the Glenelg River, rising near the Chimney Pots in the Victoria Ranges. These unite downstream near Casterton as the Glenelg River and push westward through the Western District before emptying into the Southern Ocean near the border with South Australia. The hydrology of the Gariwerd mountains therefore exerts significant influence on the surrounding plains.

Once the Europeans arrived, the creeks and rivers and reservoirs of the ranges would be vastly altered so that almost every drop of rain that fell in the mountains could be harvested and sent out, down into the plains below.

Soils, flora and fauna

At the end of the twentieth century, one-third of all native plants in Victoria could be found growing in Gariwerd, including over 975 native plant species and 75 orchid species. Many are endemic to the region – that is, not found growing anywhere else in the world. Nearly 170 species of threatened flora and fauna are found in the park, of which many are endemic (Table 1.1). The Grampians pincushion lily (Borya mirabilis) is both endangered and endemic, and now known only to grow on a single rocky outcrop in Gariwerd.¹² Relics of the time long ago, when the land formed part of Gondwana, can be found in the most moist and fertile parts of the ranges. The myrtle beech (Nothofagus cunninghamii) and southern sassafras (Atherosperma moschatum) might have plausibly once grown here, while tree-ferns – including the soft and rough tree-ferns (Dicksonia antarctica and Cyathea australis, respectively) can still be seen in the darker, wetter parts of the ranges, deep within shaded, moist gullies.¹³ While the coast banksia (Banksia integrifolia) speaks to a time when Gariwerd was part of a coastal promontory, shiny tea-tree (Leptospermum nitidum) and hazel pomaderris (Pomaderris apetala) are refugees from the inundation of the Bass Strait 11 000 years ago – they are found in Tasmania and Gariwerd, but nowhere else in Victoria.¹⁴

The flora and fauna of Gariwerd live in natural communities that form around the geological features of the ranges. Millions upon millions of years of weathering and erosion have produced a range of soils in and around the mountains and have contoured the peaks and valleys in a variety of ways. The soils of Gariwerd are often shallow, stony and sandy, sometimes sitting as little as 30 cm above the underlying bedrock. On some slopes and plains, the soil is sandier, while in valleys especially the soil is deeper and richer. In the east, south, and west, the plains are covered in a surface layer of sandy loam, while clay dominates in the north. In low-lying areas of the ranges, the heavier, clayey soils hold much water. When these soils are combined with granitic outcrops, mineral content and salinity can be higher, and where forests have been cleared for farmland, the water-table has risen, causing dryland salinity. Combined with levels of exposure to the weather and the availability of water, this diversity has produced a myriad of plant and animal habits.¹⁵ Such is the relationship between soils and vegetation that early European settlers learnt to use types of forest vegetation to identify which areas held fertile soils appropriate for agriculture. On the other hand, some of the poorest and most infertile soils, ignored by Europeans, provide some of the most biologically rich and interesting environments.¹⁶

Table 1.1. Endemic threatened and high priority flora species recorded in the Grampians National Park

Source: Parks Victoria (2003) Management Plan for Grampians National Park. Department of Sustainability and Environment, Melbourne.

At the highest peaks – in subalpine areas such as Mount William, Mount Rosea and Mount Abrupt – a healthy Grampians gum (Eucalyptus alpina) could, in the right conditions, grow up to 20 m high. Otherwise the extreme climate means tree cover is sparse; unless they find shelter in rock crevasses, most trees are gnarled and their growth stunted. Smaller plants struggle to grow, too, and foliage is tough and leathery. The Grampians banksia (Banksia saxicola), mountain correa (Correa lawrenceana), rosy bush-pea (Pultenaea subalpina), and the Victorian Christmas bush (Prostanthera lasianthos) can also be found in the high subalpine reaches of the ranges.

The mountains otherwise form the westernmost limit of tall, open forests in the state. Here can be found the tallest trees. In moist, dark, and cool gullies and on the eastern slopes of the ranges are wet sclerophyll forests, including most commonly messmate stringybark (Eucalyptus obliqua) and mountain grey gum (Eucalyptus cypellocarpa). On the middle and lower slopes of the ranges are dry sclerophyll forests, made up of medium-sized trees including brown stringybark (Eucalyptus baxteri) and a low understorey of pea-plants, heaths and grasses, punctuated by a middle layer of shrubs, including acacias, banksias and hakeas. On the lowest slopes, before opening into plains and open ranges, are shrub woodlands. The dominant species in Victoria Valley is the distinctive river red gum (Eucalyptus camaldulensis). In other areas of shrub woodlands, the yellow box and yellow gum (Eucalyptus melliodora and Eucalyptus leucoxlyon) are the most common trees and are interspersed with manna gum (Eucalyptus viminalis), long-leaved box (or bundy, Eucalyptus goniocalyx), and river red gum. Below these trees can commonly be found an understorey of blackwood (Acacia melanoxylon) and silver banksia (Banksia marginata), while in areas with an abundance of water the desert banksia (Banksia ornata) can be ubiquitous, as can varieties of tea-tree (Leptospermum) and dense shrubs of cross-leaf honey-myrtle (Melaleuca decussata) in moister soils.

In natural low-lying areas and around artificial reservoirs can be found swampland, where many plants are of a low, ground-hugging kind, such as the common swamp goodenia (Goodenia humilis), often growing alongside smaller plants including trailing pratia (Pratia pedunculata) and swamp isotome (or blue star creeper, Isotoma fluviatilis). Often in these swampy areas, there are many species of rushes, and the only tree species is the river red gum growing in dense colonies. Moving away from sources of water, on the edges of swampland as vegetation begins to build up again can be found silver banksias and yellow gum, as well as prickly tea-tree (Leptospermum juniperinum) and cross-leaf honey-myrtle. In the less well-vegetated heathlands verging on swampy areas there are few trees, but flame heath (Astroloma conostephioides), scrub sheoak (Allocasuarina paludosa) and Victoria’s floral emblem, common heath (Epacris impressa) are often present, while in heath woodlands can often be seen many common heathland species, as well as trees such as the long-leaved box (Eucalyptus goniocalyx) and shining peppermint (Eucalyptus nitida) growing alongside silver bankisas and various tea-tree species. Bordering rivers and creeks can be found a range of plants that are well adapted to the fluctuating environments. Together with mat-forming groundcovers, shrubs and aquatic plants, ferns are common in areas that are constantly moist and wet. Beside streams grow soft water-ferns (Blechnum minus), and bordering shaded waterways and on moist forest slopes is the fishbone water-fern (Blechnum nudum). Scrambling coral and pouch coral ferns (Gleichenia microphylla and Gleichenia dicarpa) grow densely along creeks and waterways and on moist forest flats, where they sometimes climb through tea-trees.

On the plains around Gariwerd and some low-lying areas between the ranges is savannah woodland, mostly open grassy plains punctuated, sporadically, by trees – generally the river red gum, but also the yellow box and yellow gum – and with little understorey. In the northern and north-west plains, between Halls Gap and Stawell to the east, for example, or between Zumsteins and Horsham to the west – are bull-oaks (Allocasuarina luehmannii), while the large drooping sheoak (Allocasuarina verticillata) can also be found in the savannah woodlands of Gariwerd.

Readily seen across the ranges are Austral grass-trees, on which strongly scented cream flowers are produced on stems up to 3 m high. Like many species in the mountains, they are particularly well adapted to bushfire and will be seen flowering in their wake (Plate 1.2). Perhaps the best known and most popular flora of Gariwerd are its rich and colourful wildflowers – some of the busiest periods for visitors in the Grampians National Park are during its wildflower season in September, October and November (Plate 1.3). More than 75 terrestrial orchid species have been recorded in the ranges. Less charismatic species include 137 species of mosses and 54 species of liverworts. There are also around 500 different species of fungi. Over 200 exotic and native introduced plants have been recorded in the park, primarily in small areas at its boundaries; these include a number of environmental and noxious weeds.

In association with its wide range of plant communities, Gariwerd has a high diversity of fauna. It is home to at least 230 species of birds, 40 mammal species, 30 reptile species, 11 amphibian species, and six native fish species.¹⁷ In the twentieth century, the descendants of Gondwanan mammals still lived in the mountains, including two egg-laying monotremes, the platypus (Ornithorhynchus anatinus) and short-beaked echidna (Tachyglossus aculeatus). Common ringtail possums (Pseudocheirus peregrinus) and other descendants of ancient marsupials that migrated to Australia 50 million years ago were found in abundance in Gariwerd, as were the agile antechinus (Antechinus agilis) and dusky antechinus (Antechinus swainsonii), common and fat-tailed dunnarts (Sminthopsis murina and Sminthopsis crassicaudata) and the long-nosed potoroo (Potorous tridactylus). The stocky southern brown bandicoot (Isoodon obsulus) scratched in the ground for insects, spiders, and worms, while koalas (Phascolarctos cinereus), introduced to the ranges in the 1950s, rested in the trees. A variety of kangaroos and wallabies are common in the area, while eleven species of bats have been recorded. The habitats of Gariwerd, today, are of particular importance to the heath mouse (Pseudomys shortridgei), smoky mouse (Pseudomys fumeus), and brush-tailed rock wallaby (Petrogale penicillata).¹⁸

Today, as leaves from the tall trees of the open forest areas of Gariwerd drop to the ground they form a layer of deep, moist litter, providing an abundant food resource for a variety of animals, including ground-feeding birds, such as the secretive, Bassian thrush (Zoothera lunulate) and the handsome brush bronzewing (Phaps elegans). Fourteen species of honeyeater can be found in the crowns of trees, especially when eucalypts are in flower. The trees are home to rosellas, parrots, lorikeets, corellas and a variety of cockatoos, including the distinctive gang-gang (Callocephalon fimbriatum), and both red-tailed and yellow-tailed cockatoos (Calyptorhynchus banksii and Calyptorhynchus funereus). In the lower reaches, a range of forest dwellers are provided with shelter and food, including fantails, babblers, cuckoos, currawongs, flycatchers, robins, wrens, warblers, starlings, magpies, wattlebirds, swallows, thrushes and thornbills. Near water sources can be seen bitterns and brolgas, cormorants and crakes, snipes and spoonbills, as well as ducks, egrets, grebes, moorhens, plovers, sandpipers, swamphens, swans, teals and terns. At night, tawny frogmouths (Podargus strigoides), nightjars, and a variety of owls emerge. In and around Gariwerd are birds of prey, including eagles, falcons, harriers, goshawks, sparrowhawks, kestrels and kites; kookaburras and other kingfishers can be found, and the emu is commonly sighted.

As well as birds and mammals, Gariwerd is home to turtles, lizards, including geckos, dragons, skinks and lace monitors (Varanus varius), and a variety of species of snakes, including several highly venomous species such as the eastern brown snake (Pseudonaja textilis) and tiger snake (Notechis scutatus). There are at least 12 species of froglets, frogs and toads, and six native fish species. Yabbies and crayfish can be found, including the protected western swamp crayfish (Gramastacus insolitus). The range of introduced mammals includes dogs, cats, foxes, mice, rats, rabbits, hares, goats and deer, and there are introduced fish species such as perch, trout and carp.

The present state of Gariwerd – perhaps the most important botanical reserve in Victoria – is the product of millions of years of change and transformation. From the late Pleistocene onwards, the mountains gradually became more heavily vegetated, and the plains to their north and south became slowly less arid. Changing temperatures and rainfall levels provided more water in the ranges themselves and for the rivers, creeks, and lakes surrounding them. Its environment had become more hospitable to a myriad of plants and animals, many of which we see today – and many of which are now under stress from environmental change. For the past 20 000 years the first Australians have watched these changes to the natural environment of Gariwerd. They have witnessed the transformation of the ranges, and Gariwerd’s place in their cultural environment – its role in their lives – has changed too.

Endnotes

1.Mitchell T (1839) Three Expeditions into the Interior of Eastern Australia. Vol. 2. T & W Boone, London, p. 175.

2.Mitchell (1839), p. 182.

3.Mitchell (1839), p. 183.

4.Mitchell (1839), pp. 185–186.

5.Mitchell (1839), p. 189.

6.Cayley RA, Taylor DH (1997) ‘Grampians special map area geological report’. Geological Survey of Victoria Report 107. Geological Survey of Victoria, Melbourne.

7.Willis JH (1971) Vegetation of Western Victoria. In The Natural History of Western Victoria. (Eds MH Douglas and L O’Brien) pp. 24–34. Australian Institute of Agricultural Science, Horsham.

8.Jones RN, Bowler JM, McMahon T (1998) A high resolution Holocene record of P/E ratio from closed lakes, Western Victoria. Palaeoclimates 3, 51–82; Jones RN, Bowler JM, McMahon T (2001) Modelling historic lake levels and recent climatic change at three closed lakes, Western Victoria, Australia (c. 1840–1990). Journal of Hydrology 246, 159–180. doi:10.1016/S0022-1694(01)00369-9

9.D’Costa D, Edney P, Kershaw AP, De Deckker P (1989) Late Quaternary Palaeoecology of Tower Hill, Victoria, Australia. Journal of Biogeography 16(5), 461–482. doi:10.2307/2845109

10.Luly JG (1993) Holocene environments near Lake Tyrrell, semi-arid northwestern Victoria, Australia. Journal of Biogeography 20, 587–598. doi:10.2307/2845516

11.Bird C, Frankel D (2005) An Archaeology of Gariwerd: From Pleistocene to Holocene in Western Victoria. University of Queensland, Brisbane.

12.Parks Victoria (2003) Management Plan for Grampians National Park. Government of Victoria, Department of Sustainability and Environment, Melbourne.

13.Calder J (1987) The Grampians: A Noble Range. Victorian National Parks Association, Melbourne.

14.Willis JH (1971) Vegetation of Western Victoria. In The Natural History of Western Victoria. (Eds MH Douglas and L O’Brien) pp. 24–34. Australian Institute of Agricultural Science, Horsham.

15.These descriptions of plant communities and associated species in Gariwerd are primarily derived from Elliot R (1984) A Field Guide to the Grampians Flora. Algona Publications, Melbourne, and Calder (1987).

16.Calder (1987).

17.These descriptions of Gariwerd animal species are primarily derived from the factsheets ‘Grampians National Park: Mammals, Reptiles, Amphibia, Fishes & Crustaceans’ and ‘Grampians National Park Bird List’, both available from Brambuk: The National Park & Cultural Centre, Halls Gap.

18.Parks Victoria (2003).