Australia’s Most Overlooked Geological Oddity: Jarnem Keep

A Geological Oddity in Northern Australia

Most people think Australia’s strangest stone landscapes sit out on the coast, shaped by waves or carved from limestone dunes. But hidden in the far north, right near the border with Western Australia, there’s a place that looks like a ruined stone city rising straight out of the bush. Tall domes. Narrow towers. Walls striped in iron-red and grey. At first glance, it feels impossible that this landscape wasn’t built. It looks designed. Deliberate. Almost architectural. And yet, this place was never constructed at all. What you’re seeing is what remains after almost everything else disappeared.

This landscape sits at Jarnem, in Keep River National Park in the Northern Territory. It’s often quietly compared to the Bungle Bungles, and sometimes loosely lumped in with the Pinnacles of Western Australia. But Jarnem doesn’t really belong to either group. Its shapes tell a much stranger story — not of rocks being carved into form, but of an entire sandstone world being dismantled piece by piece, leaving behind only its toughest fragments.

To understand why Jarnem looks the way it does, you first have to forget the idea that these towers were sculpted into existence. That’s the wrong mental picture. These aren’t monuments that rose up. They’re survivors. What you’re walking through is a graveyard of stone, where the only structures left standing are the ones that resisted collapse just a little longer than everything around them.

Hundreds of millions of years ago, this part of northern Australia looked nothing like it does today. Instead of isolated domes and narrow ridges, there was a broad sandstone surface stretching across the region. Rivers flowed across it. Sediments piled up. Sand, gravel and silt were laid down in shifting environments that changed from shallow marine settings to river plains as the ancient Bonaparte Basin evolved. These sandstones, now known as formations like the Border Creek Formation and the Kelly’s Knob Sandstone Member, were deposited during the Devonian and Early Carboniferous, when life on land was still experimenting with forests for the first time.

At the time, there was nothing dramatic about these rocks. They weren’t cliffs or towers. They were flat-lying sheets of quartz-rich sand, buried and compacted, layer upon layer. The drama came later.

As Australia drifted north and climates shifted, the Keep River region went through long periods of deep chemical weathering. This wasn’t fast erosion. It was slow, insidious decay. Water soaked into fractures. Heat expanded minerals. Iron oxidised. Cement weakened. Entire rock masses were altered from the inside out while still sitting in place. The sandstone didn’t crumble yet — it softened. And that step matters more than most people realise.

Because once the climate shifted again, and erosion finally accelerated, the landscape was already primed to fail.

When rivers began cutting down and surfaces started to strip away, the weakened sandstone collapsed unevenly. Some zones were slightly better cemented. Some beds were a little more resistant. Some fractures drained better than others. And those tiny differences decided everything. The weaker rock vanished into sand and soil, feeding the surrounding plains. The stronger remnants stayed behind, standing alone as the ground around them dropped away.

That’s how Jarnem formed. Not by carving towers out of rock, but by removing almost all of the rock and leaving only the last stubborn pieces behind.

This is why the shapes feel so strange. The domes and pinnacles aren’t aligned like wind-carved features or solution pipes. They follow the hidden logic of bedding planes, fractures and subtle internal strength differences. Some stand wide and rounded. Others narrow into fins or walls. Many show horizontal banding — iron-rich layers alternating with paler sandstone — not because someone painted stripes onto them, but because moisture, microbes and oxidation behave differently across those layers once the rock is exposed.

It’s also why this landscape feels fragile when you’re actually there. Unlike the hard, cliff-forming sandstone of the Kimberley plateau to the west, the Keep River sandstones are less durable. The research makes this point quietly but clearly: this is not a stable stone fortress. It’s a landscape actively falling apart.

Even today, the pinnacles are shedding grains. Domes flake. Blocks slump. Sand sheets accumulate downslope. Cosmogenic dating and luminescence studies show that erosion and deposition are ongoing processes here, not ancient events frozen in time. Jarnem isn’t a finished landform. It’s a moment caught mid-collapse.

And that’s where the scale of the story really kicks in.

Because when you look at one pinnacle, it’s tempting to see it as a standalone feature. But the reality is far larger. Each dome is a remnant of a surface that once stretched for kilometres. Every isolated tower marks the former height of the land. The space between them — now filled with grasses, soils and floodplains — is the volume of rock that’s already been erased.

In other words, the real landform at Jarnem is invisible. What you’re seeing is the negative space.

This perspective flips the usual way we think about geological monuments. We tend to imagine landscapes being built upward or sculpted into shape. Jarnem tells the opposite story. It’s subtraction geology. A landform defined not by what exists, but by what’s gone missing.

And that absence has shaped human history here as well.

As the sandstone surface broke down, it created overhangs, alcoves and shelters along escarpments and domes. These became places of refuge, art and ceremony for Aboriginal people over tens of thousands of years. The same processes that dismantled the landscape also created the spaces where culture was preserved. Rock shelters formed because of differential weathering. Art survived because those shelters stayed dry. Even the placement of sites reflects the slow disintegration of stone.

What makes Jarnem especially unusual is how easily it gets overlooked.

It doesn’t have the fame of Uluru. It doesn’t have the dramatic isolation of the Pinnacles. It sits quietly between better-known geological provinces — too sandstone-rich to be karst, too eroded to be a plateau, too inland to be coastal. And because of that, it slips through the cracks of popular geology.

But if you compare it carefully, Jarnem occupies a rare middle ground.

Unlike the Western Australian Pinnacles, which formed from young coastal limestone dunes during the late Pleistocene, Jarnem’s pinnacles are ancient — their raw material laid down more than 300 million years ago. Unlike the Bungle Bungles, which retain broad dome fields across a still-elevated plateau, Jarnem represents a later stage of destruction, where isolation has already begun. It’s not the birth of a stone city. It’s the aftermath.

And that’s why it qualifies as a genuine geological oddity.

Most landscapes show us construction or stability. Mountains rise. Plateaus persist. Coasts retreat. Jarnem shows collapse in slow motion. It’s a place where geological time is visible not as grandeur, but as erosion winning, grain by grain.

If you were to rewind the landscape, the pinnacles wouldn’t grow taller. They’d dissolve back into a continuous surface. The domes would merge. The gaps would close. The stone city would vanish — because it never truly existed in the first place.

What remains today feels mysterious because it contradicts our instincts. We’re wired to assume complexity comes from building up. Jarnem proves that complexity can also come from being stripped away.

So when people compare Jarnem to the Pinnacles or the Bungle Bungles, they’re only half right. The resemblance is visual, not genetic. Jarnem isn’t a sibling to those landscapes. It’s a cousin shaped by loss rather than form.

And that’s what makes it so compelling.

You’re not walking through a monument. You’re walking through the remains of an entire geological surface that once stretched across northern Australia — now reduced to scattered towers quietly surrendering back to sand. Few people know it exists. Fewer still understand what they’re looking at.

But once you do, it’s hard to unsee.

Jarnem Keep isn’t just a strange landscape hidden in the Northern Territory. It’s a reminder that some of Australia’s most extraordinary geological stories aren’t about what the land has become — they’re about what it’s in the process of losing.

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