The Great Dividing Range is Australia’s most significant mountain system, stretching roughly 3,500 kilometres along the continent’s eastern edge from the Cape York Peninsula in far north Queensland to the Grampians in western Victoria. Despite its name, it is not a single dramatic ridge but a series of plateaus, ridges, hills, and low mountain ranges that collectively form a continental drainage divide, separating rivers that flow east toward the Pacific Ocean from those that flow west and south into the vast interior. It ranks among the longest mountain ranges on Earth, and its influence on Australian climate, water resources, and biodiversity runs deep.
How the Range Formed
Australia is often described as the flattest inhabited continent, so the presence of a mountain chain spanning its entire eastern flank deserves some geological explanation. The Great Dividing Range began to rise roughly 80 to 100 million years ago near the eastern margin of the Australian landmass, as the Tasman Sea opened and New Zealand rifted away from what is now Australia’s east coast. That tectonic separation caused the eastern edge of the continent to uplift, and the basic shape of the range dates to that period.1ResearchGate. The Geology of Australia
The geology beneath the range is far from simple. It contains sedimentary strata and granites older than 300 million years, predating the uplift itself by a wide margin. On top of that ancient foundation, more recent volcanic episodes have scattered basaltic rock across much of the range, particularly in areas like the Atherton Tableland in Queensland and parts of western Victoria.1ResearchGate. The Geology of Australia The result is a patchwork of rock types and ages, which is part of why the range looks so different from one end to the other. In the tropical north, it can be a low, rolling plateau barely noticeable from ground level. In the southeast, it includes Australia’s highest peaks.
What It Actually Looks Like
People who hear “mountain range” and picture jagged alpine peaks will be surprised by most of the Great Dividing Range. For long stretches, especially through central and northern Queensland, the range is a broad, gently rolling upland. Elevations along much of its length sit between 300 and 1,600 metres, and the crest can be hard to identify without a map. In some places it is little more than a subtle rise in the landscape that happens to send water flowing in different directions.
The character shifts dramatically in the southeast. The Australian Alps, a section of the range straddling the border of New South Wales and Victoria, contain Australia’s highest peaks. Mount Kosciuszko, at 2,228 metres, is the continent’s tallest summit. In winter, the Australian Alps accumulate enough snow to support a ski industry, which surprises visitors who associate Australia exclusively with heat and desert. The Blue Mountains west of Sydney, another well-known section, are carved from sandstone plateaus into deep valleys and dramatic cliff faces. And in far north Queensland, the range backs up against the wet tropics, where some of the oldest rainforest on Earth clings to its eastern slopes.
This variety means the Great Dividing Range is not one landscape but many. Dry eucalyptus woodland, tropical rainforest, alpine herbfields, temperate grasslands, and subalpine snowgum forests all sit within its boundaries, sometimes within a few hundred kilometres of each other.
The Continental Divide and Its Rivers
The range’s most important role, practically speaking, is as a water divide. Rain falling on the eastern side feeds short, fast-flowing rivers that drain into the Pacific. Rain falling on the western side feeds much longer, slower river systems that flow inland, including the Murray-Darling Basin, which supplies water to a huge portion of Australia’s agricultural land. This split has shaped where Australians live, farm, and build cities. The well-watered eastern coastal strip supports the majority of the population, while the drier western side of the range grades into the vast interior.
Because the range sits close to the eastern coast, the rivers running east are typically short and steep. They can flood quickly after heavy rain and are generally not suitable for large-scale irrigation. The rivers running west, on the other hand, travel enormous distances through increasingly flat, dry country. By the time the Darling River reaches its confluence with the Murray, it has crossed landscapes that look nothing like the green uplands where it started.
This geographic reality has driven some of Australia’s most ambitious engineering projects. The Snowy Mountains Hydro-Electric Scheme, built between 1949 and 1974, diverts water from rivers that would naturally flow east and sends it westward through tunnels bored through the range, generating hydroelectric power along the way. The scheme substantially changed the hydrology of the Snowy River below the diversion point. Annual, monthly, and peak flows were significantly reduced along 352 kilometres of channel after 1967, and the first 70 kilometres of the river contracted as a result, with tributary mouth bars reworking into downstream pools and benches.2Regulated Rivers: Research & Management. River rehabilitation from the hydrogeomorphic impacts of a large hydro-electric power project: Snowy River, Australia The Snowy scheme is a striking example of how the range’s role as a divide creates both opportunity and ecological cost.
Biodiversity Along the Range
The Great Dividing Range is one of Australia’s richest corridors for plant and animal diversity. Its north-south extent means it links tropical ecosystems in Queensland to temperate and alpine ecosystems in Victoria, and its elevation creates habitat variety that lowland areas cannot match. Many species live in narrow elevation bands along the range, especially in the alpine and subalpine zones of the southeast and the wet tropical uplands of the northeast.
In the northeast, the Gondwana Rainforests of Australia, a World Heritage-listed collection of rainforest remnants, cling to the range’s eastern slopes. These forests contain species from lineages with deep evolutionary roots stretching back to when Australia was still part of the supercontinent Gondwana. Researchers studying refugial dynamics in these forests have used species distribution models to identify areas that have remained climatically stable for certain rainforest species from the Last Glacial Maximum through to projected conditions in 2090, helping to map where ancient lineages are most likely to persist as the climate shifts.3Applied Vegetation Science. Contraction–Expansion Dynamics Shape Refugia and Recolonisation Processes in the Gondwana Rainforests of Australia World Heritage Area
In the southern alpine and subalpine zones, the fauna is distinctive and increasingly vulnerable. Species like the broad-toothed rat and the mainland dusky antechinus depend on snowpack and dense ground cover. The alpine treeless zone, found above roughly 1,800 metres, supports plant communities found nowhere else in Australia, including sphagnum bogs and alpine herbfields. These bogs are especially significant because they act as natural water filters and storage, releasing water slowly into downstream catchments.
Fire and the 2019–2020 Megafires
Fire is a natural part of most Australian landscapes, but the scale of the 2019–2020 bushfire season, known as Black Summer, was unprecedented in recorded history and hit large sections of the Great Dividing Range hard. The fires burned through millions of hectares of forest, including vegetation types that are not adapted to frequent or intense fire.
Gondwanan rainforest communities were among the most vulnerable. These forests evolved in moist conditions where fire was historically rare, so they lack the regrowth strategies that eucalyptus woodlands have developed over millions of years. Research into the megafires found that these rainforest communities were severely burnt in several bioregions, and that the fires caused a taxonomically diverse array of species with broad ranges to suffer extensive losses of mature individuals. The concern is that depleted resilience may lead to regenerative failure and permanent biogeographic change in some of these forest types.4Nature Communications. Implications of the 2019–2020 megafires for the biogeography and conservation of Australian vegetation
For the range’s animal species, the picture is equally troubling. In subalpine habitats, researchers studying small mammal populations found that all species in their study declined sharply after fire, with the slowest recoveries seen in the broad-toothed rat and the mainland dusky antechinus. The interaction between reduced snowpack, wildfire, and predation by foxes creates a compounding threat that is difficult to manage.5PubMed Central. Fire and Snow: Effects of Snowpack Variation and Wildfire on Small Mammal Dynamics in Sub-Alpine Habitats
Climate Change in the Australian Alps
The alpine and subalpine sections of the Great Dividing Range are among the ecosystems most sensitive to warming temperatures in Australia. Snow cover has already decreased over recent decades, and the trend is projected to continue. For species that depend on insulating snowpack through winter, like the broad-toothed rat, shallower snow means colder ground temperatures, less protection from predators, and reduced survival. Research found that populations of this species often declined following winters with shallow snow cover, and that the timing of snowmelt influenced population numbers of multiple small mammal species in the following warmer months.5PubMed Central. Fire and Snow: Effects of Snowpack Variation and Wildfire on Small Mammal Dynamics in Sub-Alpine Habitats
Expert predictions for the Australian Alps paint a sobering picture for 2050. A structured expert assessment estimated that most alpine vegetation communities would decline in extent by mid-century, with only woodlands and heathlands predicted to expand, likely creeping upslope into areas currently occupied by treeless alpine vegetation. At the species level, alpine plants showed a wide range of predicted outcomes, with some expected to increase, some to decline, and some to hold steady. Animals, however, were almost universally predicted to decline or remain stable at best, with species tied to aquatic or semi-aquatic habitats especially likely to lose ground.6PubMed Central. Predicting species and community responses to global change using structured expert judgement: An Australian mountain ecosystems case study The pattern is one of upslope squeeze: as lower-elevation vegetation pushes higher, true alpine species have less and less room.
Feral Horses in the High Country
One of the most contentious conservation issues along the Great Dividing Range involves feral horses, often called brumbies. Populations of feral horses roam parts of Kosciuszko National Park in New South Wales and adjacent alpine parks in Victoria, and they have become a politically charged symbol. Some Australians view brumbies as part of the nation’s cultural heritage, linked to bush poetry and frontier mythology. Conservation scientists see them as a destructive introduced species degrading irreplaceable habitats.
The ecological evidence is clear. Research in the Australian Alps confirmed that feral horses endanger threatened species and extensively damage critically endangered bog communities. These bogs, built up over millennia by slow accumulation of organic material, can take thousands of years to recover from trampling. Critically, the damage accumulates over time even when horse numbers are low: impacts were documented with populations of roughly 100 animals.7Ecological Management & Restoration. Impacts of feral horses in the Australian Alps and evidence‐based solutions
The damage extends to specific threatened species. The southern corroboree frog, one of Australia’s most endangered amphibians, breeds in shallow pools edged with leaf litter in subalpine bogs. A study comparing areas with and without horse access found that pool-edge litter was 1.9 times deeper in areas protected from horses than in areas where horses could graze and trample. Reduced litter depth means degraded breeding habitat, which in turn threatens reproduction for a species already on the brink.8Wildlife Research. Feral-horse impacts on corroboree frog habitat in the Australian Alps Management of feral horse populations remains politically difficult, but the scientific case for reducing their numbers in sensitive alpine areas is strong.
Human Settlement and the Range’s Cultural Footprint
The Great Dividing Range has shaped Australian settlement patterns since long before European arrival. Aboriginal Australians have lived along and within the range for tens of thousands of years, with different language groups occupying different sections. The Bogong moth migrations to the Australian Alps, for instance, drew Aboriginal groups from lowland areas into the mountains for seasonal gatherings. European colonists found the range a significant barrier to inland expansion. The first crossing by European settlers occurred in 1813, when Blaxland, Lawson, and Wentworth found a route across the Blue Mountains west of Sydney, opening the western plains to pastoral settlement.
Today, most of Australia’s largest cities sit on the coastal side of the range, benefiting from the rainfall it wrings from easterly weather systems. Sydney, Brisbane, Melbourne, and Cairns all owe their water supply partly to catchments in or near the range. The range also supports a tourism economy built around its varied landscapes: the Blue Mountains, the Daintree Rainforest, the ski fields around Mount Hotham and Thredbo, and the scenic hinterland behind the Gold Coast all draw millions of visitors annually. For many Australians, the range is the backdrop to daily life without necessarily being recognized as a single continuous geographic feature, which is part of what makes it an unusual kind of mountain system: enormous in scale, deeply consequential, and easy to overlook from any one vantage point.