An Untouched Goldfield in Victoria - Hidden Beneath Lava

The Untouched Goldfield Hidden Beneath Lava

You know what’s frustrating? Knowing where a huge quantity of gold is — and being completely unable to get to it.

Come with me on a journey across the Western District volcanic plains — one of the largest volcanic plains on Earth, stretching from Melbourne’s west through Geelong and all the way to Hamilton. Beneath this flat, fertile landscape lies a hidden world: ancient rivers, long gone from the surface, that once ran rich with gold.

Today, they’re locked away under vast sheets of basalt — the remains of enormous lava flows that smothered valleys millions of years ago. And here’s the kicker: almost no one has ever properly explored them. Very few modern companies have drilled through the basalt to sample the ancient gravels. That means the gold sitting under this landscape has been untouched for thousands of years — and it’s still there, waiting.

But how can I be so sure that an enormous amount of gold exists below the surface? Well, we need only look at the geology of the area, and the historical mining reports.

Volcanic eruptions began in Victoria within the past 6 million years. Prior to that, the western district was very similar, geologically speaking, to the goldfields north of it. Now the old miners weren’t dumb, they knew that beneath the massive amount of lava here, lies gold. They worked it far south, almost to the town of Cressy. And after that, nothing.

This is the southernmost mine in the district. The Great western and Woady Yaloak Junction Co.

As you can see, the mine wasn’t too far from Lake Martin and the other volcanic lakes. In a report on trove, it’s stated that they dug to a depth of 200 feet, which is about 61 meters below the surface, where they found dark brown clay containing freshwater shells. If we look on Geovic, we can see that mines operated along these deep leads, which is the Australian term for a buried river channel. But the Great Western and Woady Yaloak Junction Co. operated south of where the documented deep lead quote unquote, “ends”, so they knew that beneath the basalt here, gold was present in the former river channels that were since buried beneath volcanic lava. Not much is known about this mine. What is known, is that they commenced operation sometime in the early 1860s.

Now as you can see, there are very clearly two buried rivers that have been chased to a certain point. They’re running south. And you can bet they do not stop here.

So, this begs the question, why didn’t the miners continue chasing it? There are a few reasons that could explain why that we will get into shortly.

Once Were Rivers of Gold

So prior to the volcanic eruptions, broad, golden rivers once coursed across here. Water flowed from the ancient highlands – carrying silt, gravel, and gold – across this landscape. These streams meandered from the uplands toward the sea in the south, depositing rich alluvial gold in their beds and bends.

Buried by Fire and Stone

Then came the eruptions. They poured out from hundreds of eruption points, flowing like molten rivers into the low valleys. Flat lava fields spread from Melbourne to Hamilton, cooling into hard basalt rock that entombed the old stream beds beneath. Some volcanic flows were relatively thin, but over time, they filled entire valleys up to 50-60 meters deep, sealing ancient gold-bearing gravels under an impenetrable cap of rock. The result was a vast, windswept volcanic plain, deceptively flat and featureless, hiding a dramatic secret below its soils.

The Gold Rush That Passed By

In the early days, prospectors had little reason to stop on these seemingly barren flats; the gold was there but buried far below thick lava rock they couldn’t easily penetrate. Miners of the 19th century focused on easier pickings, flocking to accessible alluvial fields and reef outcrops. In areas where ancient leads ran under basalt, prospectors would sometimes trace a rich gully or creek to the point where it vanished beneath a layer of “bluestone” lava.

Yet the lure of those hidden riches did not go entirely unnoticed. By the 1860s, geologists understood that tremendous wealth lay in the “buried auriferous river deposits” of Victoria. They realized that many ancient valleys filled with gold had been covered by newer rocks. An influential 1907 paper observed that “the quantity of buried auriferous gravels which exist in Victoria is enormous, but the amount of their actual development has been infinitesimal”. In other words, only a tiny fraction of the gold trapped under lava had been won. Miners in the 19th century simply couldn’t reach most of it, lacking the costly deep shafts, heavy-duty pumps, and advanced methods required to tunnel through thick basalt and manage the underground water in those buried riverbeds. After a few bold attempts, even some well-funded companies halted when confronted with the Western Plains’ basalt barrier. Thus, as the surface gold ran out elsewhere, an untold fortune remained stranded beneath the volcanic plain – known to science, but just out of reach.

But here’s the thing: this region is just as old and built on the same Ordovician bedrock that lies beneath the goldfields to the north. That means it’s not only the ancient, buried rivers that have been left untouched — it’s likely the ground here holds the same degree of gold enrichment as the exposed country beyond the lava’s reach. Beneath the basalt could be gold-rich quartz reefs, placer deposits, and alluvial fields identical in origin to those that made the northern goldfields famous. For the past six million years, those riches have been hidden under successive lava flows — but below that dark volcanic cap lie original, unworked goldfields, born from the same erosion of auriferous quartz reefs as their counterparts to the north.

The Basalt Barrier – A Silent Challenge

Standing on the Western District plain today, you’d never guess what lies below. The land is a patchwork of grazing paddocks and stony rises, dotted by the occasional extinct volcano cone on the horizon. Underfoot, however, is solid basalt rock – nature’s concrete, tens of meters thick in many places. This rock sealed away the ancient river channels like a time capsule. For would-be gold explorers, the basalt cover is a formidable adversary.

But this isn’t the only reason mining did not occur here as the Western District had another major problem.

Water.

As you can see, the land is dominated by volcanic lakes.

The water table is shallow, and groundwater flooding was absolutely a major limiting factor, and it likely played the single biggest role in stopping further exploration southwards. The district sits at one of the lowest points of the Victorian Volcanic Plain — almost at lake level. The Woady Yaloak Creek system drains into Lake Corangamite, and the land in that stretch is barely above the lake’s surface elevation. This means the regional water table is at or near the surface for much of the year and sinking a shaft here, even into the overlying basalt, would almost immediately intersect saturated ground. On top of this, old river valleys under the basalt often act as confined aquifers. The gravel layers are highly permeable and the overlying basalt traps and pressurises the groundwater. When shafts are sunk into these gravels, the water doesn’t just seep in — it can rush in under pressure, quickly flooding workings.

Adding to this was a hard limit: in the late 19th century, steam-powered pumps could only lift so much water.

These challenges meant that vast areas of the Western District remained untouched by the gold rush. The plains from Geelong all the way west to Hamilton saw little mining compared to the booming diggings elsewhere. Beneath the quiet cows and sheep grazing on rich volcanic soils, golden streams lie entombed, silently waiting. The basalt cover turned this region into a natural vault – one not easily opened with the tools of the 19th century.

Modern Hopes and New Technologies

Today, a century and a half after the first gold rush, those long-forgotten treasures under the Western District still beckon. The frustration and intrigue that opened our story – “there’s gold here, known but inaccessible” – might finally meet its resolution. Modern science and technology are now peeling back the veil on these hidden gold leads.

In recent years, researchers have begun mapping the ancient, buried rivers using sophisticated methods. Seismic surveys (much like an ultrasound of the earth) can detect the old valley shapes buried in the rock. Magnetics and gravity surveys can subtly hint at where heavier basalt gives way to lighter gravels below. Even groundwater bore data from farmers’ wells have provided clues – occasional drill holes bring up rounded river pebbles or specks of gold, betraying the presence of an old streambed below the basalt. Where the old timers could only guess, modern geologists can model entire palaeoriver systems on a computer, tracing where the gold-bearing gravels likely extend across the plains.

Most importantly, drilling technology has leaped forward. Rigs can now bore through hard basalt far more efficiently than the hand-dug shafts of yesteryear. Across Victoria, explorers are revisiting deep leads that were abandoned at the basalt’s edge.

A Hidden Bonanza Awaits

With careful, responsible exploration, Victoria’s hidden leads could be uncovered in the coming years, rewriting what we know about the state’s gold wealth. It won’t be easy – the Western Plains are keeping their gold on their own terms, demanding patience and ingenuity to unlock. But the story is far from over.

Here's the link to the video we made on this on the OzGeology YouTube Channel: