Spotlight: Devil's Marbles, NT

Local indigenous people say that these famously large, spherical, granite rocks are the fossilised eggs of the Rainbow Serpent who once roamed the NT region. Dreamtime stories of the serpent can be found in many different locations in northern Australia and today the eerie formations lie, untouched, in the area known as Devil Country.

The Devil's Pebbles, scattered over the countryside 11km north of Tennant Creek and just six kilometres to the west of the Stuart Highway, are an unusual collection of granite boulders and have long been an Aboriginal Dreaming site.

The rocks here, some weighing hundreds of tonnes, are intriguing in shape, colour and formation and seem to be piled in small heaps as if some giant from the past had picked them up and, with one mighty swipe, left them strewn across a large area of country to be found millions of years later.

They stand tall and defiant against the harsh forces of nature in this unsympathetically hot, dry landscape.

The relentless heat in the central part of the NT could easily be compared with a 'hell on earth', particularly in summer when the temperatures are often well into the 40s (degrees celsius) for days and weeks at a time.

More Pebbles down south

The Devil's Marbles, just off the Stuart Highway 108km south of Tennant Creek, are perhaps the more intriguing, precariously balancing in a unique and fascinating display.

Rising out of flat, open country, the Marbles are clearly the larger formations (just over 100km to the north), with a number of these giants measuring up to six metres in diameter and weighing several thousand tonnes.

These significant geological structures are seen today as rounded boulders which appear to be incredibly balanced as separate rocks, however, they did not start out this way.

The Marbles began as a huge granite deposit formed underneath the earth's surface. Erosion over millions of years stripped away the overlaying material and from there a continual weathering of the granite outcrop has created the shapes as they now appear.

Around the boulders is a colourful carpet of spinifex and red sand, while the occasional wattle or spindly ghost gum adds a contrasting splash of colour to this fascinating landscape.

Most of the boulders are seen to have a reddish-brown colouring caused by the oxidisation or rusting of the iron minerals in the granite surface. As wind, rain and sun continually attack, the boulders suffer a flaking process where it is almost like rotting skin peeling off the rounding shapes in a weathering action, known as exfoliation.

In millions of years from now, those who may be here to study this fascinating area will almost certainly find these devilish shapes to be significantly eroded and distinctly smaller than they are today.

Quite a few of the boulders can also be seen to be deteriorating in a different way, with very fine cracks allowing rainwater to penetrate and attack the inside of the rock. This interior weathering along the cracks often weakens the structure of the boulders to the extent that they split apart.

This takes place more rapidly when the cracks are vertical, or near-vertical, and the sheer weight of the two halves of the boulders pulls them apart. IN person, they appear as though left sliced in two by a giant axe or knife… or perhaps it is the mystical handiwork of a higher power?

Popular spot

The Devil's Pebbles are a popular picnic spot with barbecue facilities available, only a short drive from Tennant Creek, where visitors can either drive or walk through the extensive area of formations.

At the Devil's Marbles, just a few metres off the Stuart Highway, there’s a sealed roadway leading through the main section and a camping area tucked in behind the formations which, in this remote area, is a welcome stopover point for travellers either making their way north or south through the NT.

In the Devil's Marbles Conservation Reserve the camping area is maintained and patrolled by the local ranger who keeps the area clean (for a small camping fee). There are several pit toilets, neatly laid-out tables, and a number of fireplaces with barbecue plates and shady gazebo-style sun shelters provided.

Bring your own firewood, water and all supplies. The camping area has been surfaced with a layer of packed river gravel and enclosed by log fencing to prevent vehicles driving among the Marbles.

One tip: if you’re planning to stop overnight at the Marbles around the peak season (June-September), don’t leave your run too late. Arriving just before 3pm, we nabbed one of the last spots big enough for a caravan. The dirt track in is suitable for all vehicles.

Spinifex pigeons and pee-wees are quite common in the area and visit the campsites for any pickings they can find. Delicate fairy martins can be seen swooping and gliding in and around the granite boulders and their mud nests, built grain by grain with the beaks of these tiny birds, can be seen high in the rocks.

From the camping area or roadway parking areas, visitors are free to walk among the Marbles, where a series of informative signs explain local features and help keep you on track.

It's an incredible experience at any time of the day but, as with many other rock formations, they really come alive at sunset and sunrise - the weathered granite surfaces take on a reflected glow from the sun in the late afternoon and early morning, which is bleached out during the middle part of the day.

The morning and evening shadows of the boulders add intrigue to this fascinating phenomenon. And in the dark of night, the haunting silhouettes of the Marbles' balancing act will leave you pondering the wonders of Central Australia's Devil Country.