BREAKING: Scientists Discover Two MONSTROUS Volcanoes Under Australia!

The Lost Giants Beneath New South Wales: Uncovering 290-Million-Year-Old Supervolcanoes

For generations, the rolling farmlands of central New South Wales seemed serene and unremarkable — just another patchwork of quiet fields, grazing cattle, and gum trees swaying in the wind. But deep beneath this tranquil surface, sealed under hundreds of metres of sandstone, shale, and ancient sediments, lay a secret of staggering scale: the buried remains of two colossal volcanoes, silent for nearly 290 million years.

These hidden giants — now identified as the Barrett Creek Caldera and the Three Hills Caldera — once unleashed eruptions of unimaginable violence during the early Permian period, an age long before dinosaurs roamed the Earth. Their fury rivalled the largest known volcanic events in our planet’s history, producing ash clouds and lava flows capable of reshaping continents. Today, thanks to modern geophysical technology, their story is erupting into the light for the first time in hundreds of millions of years.

A World Before Dinosaurs

Around 290 million years ago, the heart of what is now New South Wales was a vastly different landscape. The supercontinent Gondwana stretched across the southern hemisphere, and the region sat along an active volcanic arc. Here, immense pressure built within the Earth’s crust until it tore open in a series of cataclysmic eruptions.

These events were so large they likely reached a Volcanic Explosivity Index (VEI) of 7 or higher — the kind of eruption that could plunge the planet into volcanic winter. Vast plumes of ash and molten rock rose into the atmosphere, while pyroclastic flows raced across the land, annihilating everything in their path. As the magma chambers emptied, the towering volcanoes collapsed inward, forming calderas — gigantic crater-like depressions several kilometres wide.

The aftermath was a shattered, smouldering wasteland buried under layers of ash, tuff, and lava, now preserved as part of the Rylstone Volcanics.

Burial and Preservation

In the millennia that followed, erosion began to soften this raw, volcanic terrain. Rain, wind, and rivers carried sediment across the scarred land, slowly burying it. An ancient inland sea spread over the region, depositing layers of sand, silt, and mud that would become the early Sydney Basin.

Swampy forests grew and died, leaving behind organic matter that would eventually form coal seams — locking the volcanic landscape beneath up to 60 metres (200 feet) of sediment. Over hundreds of millions of years, this burial preserved the calderas almost perfectly, shielding them from erosion and weathering.

By the modern era, no peaks or cliffs remained to betray their violent origins. Only gentle hills and farmlands hinted — faintly — at the scars hidden below.

Whispers from the Past

Clues to the existence of these buried supervolcanoes began surfacing in the 1980s. In 1989, prospectors from CRA (now part of Rio Tinto) found traces of gold, silver, and copper in local stream sediments. These “geochemical whispers” hinted at a rich, unseen source upstream.

This search ultimately led to the discovery of the Bowdens Silver Deposit — now recognised as Australia’s largest undeveloped silver resource, with an estimated 396 million ounces of silver equivalent. But even then, unusual volcanic rocks and mineral veins around Barrett Creek puzzled geologists. The evidence suggested a massive hydrothermal system — but where was the volcano?

The Breakthrough

The answer came only in 2023, when Silver Mines Limited launched a large-scale geophysical survey across 96 km of the Sydney Basin. Using seismic waves, magnetic mapping, gravity measurements, and electromagnetic imaging, they built a 3D picture of the landscape beneath the farmland.

The results were stunning:

Two large, circular depressions consistent with collapsed volcanic chambers.
Ring-shaped faults marking the edges of the ancient calderas.
Distinct magnetic and density anomalies showing the dense volcanic rock beneath lighter sediment.

The Barrett Creek caldera measures 4 × 4 km (2.5 × 2.5 miles). The Three Hills caldera spans 3.5 × 3.5 km (2.2 × 2.2 miles). Both remain remarkably intact, a geological rarity.

Why They Matter

The buried calderas are more than prehistoric curiosities. When volcanoes collapse, they create fractured rock systems that act like natural plumbing, allowing mineral-rich, superheated water to rise from deep within the crust. Over thousands of years, metals such as silver, gold, copper, lead, and zinc precipitate from these fluids, forming ore deposits.

This is exactly how the Bowdens deposit formed — and geologists believe Barrett Creek and Three Hills may be similar or even richer, given their apparent preservation and proximity to ancient heat sources.

At Barrett Creek, stream sediments still carry over 10 parts per billion of gold. Outcrops show quartz veins coated in pyrite and weathered gossan — strong signs of past hydrothermal activity. The rocks have undergone silicification (hardening by silica-rich fluids), a process often associated with world-class gold and silver “bonanza” veins.

Three Hills is even more intriguing. Completely buried under just 60–100 m of sediment, its volcanic structure appears untouched since the Permian. Geophysical data suggest the steep crater walls, central lava dome, and possibly even an ancient lake bed remain preserved — a geological time capsule.

Scientific and Economic Potential

To scientists, these calderas are rare, intact snapshots of ancient supervolcanoes, offering a chance to reconstruct an eruption landscape from almost 300 million years ago. They also hold vital clues to the tectonic history of eastern Australia, sitting at the margin of the Lachlan Orogen, where volcanic arcs once collided with sedimentary basins.

To industry, they could be the next great mineral frontier in New South Wales. If Barrett Creek or Three Hills host ore bodies similar to Bowdens, they could yield extraordinary concentrations of precious and base metals.

The Silent Giants

Today, standing in a peaceful paddock near Rylstone, the idea of ancient volcanoes beneath your feet feels almost impossible. The cattle graze quietly, the air smells faintly of eucalyptus, and the hills roll gently to the horizon. Yet only a few kilometres down, there are the fossilised scars of eruptions so violent they reshaped the land when Earth’s continents were still drifting into place.

The story of Barrett Creek and Three Hills is one of patience — geological patience. For 290 million years, the land kept its secret. Now, with the combined power of science, technology, and human curiosity, these silent giants are finally being revealed.