Early morning mist shrouds Kunderang Brook Valley some 800m below, as if wanting to smother its grisly past. Aboriginal massacres occurred here during the 1840s.

Early morning fog drifts across the gorge country as NPWS ranger Piers Thomas embarks on the first day of the Green Gully Circuit. Just out of shot is Cedar Creek Cottage, the start point for the walk and the former home of Alan Youdale, a stockman who managed 15,000ha of gorge country almost singlehandedly up until his death aged 83.

A Burton’s snake-lizard lazes in Green Gully Creek. These reptiles have distinctive, long, wedge-shaped snouts and scales on their heads that are fragmented and irregular. The hind limbs are minute flaps. Another unusual feature is its sleeping posture: it rests with its neck and head at a 45-degree angle to the ground. Burton’s snake-lizards aren’t venomous and can grow up to 60cm long.

The view from the Rocks Lookout. This spot provides an expansive vista of Green Gully Creek and the Apsley River Gorge, 500m below, as well as distant peaks and one of the most prominent formations in the area, Tooth Rocks.

Piers Thomas walks through the gate to Birds Nest Hut, the first of three restored stockman’s huts that are now accommodation for walkers. Stockmen Jeff O’Keefe and his father Laurie toiled in freezing conditions during the winter of 1962 to erect the hut, which stands in a small clearing next to a creek. It took less than a fortnight to build even though they had no electricity or generators to power their tools – instead they used simple hand tools such as saws and drills.

Piers leads the way to the second stockman’s hut – Green Gully Hut – which stands in a grassy clearing next to a creek and a defunct stockyard.

Piers disappears into a forest of white-topped box gums along the Rocks Trail. The route leaves this 4WD management track a little further along from here, veering down a steep tussock-clad hill which eventually leads to Green Gully Hut.

The only way is down. This section of the track is shortly after the Rocks Lookout and zigzags down a steep hill punctuated with tall grass trees, all the while providing rugged vistas of Oxley Wild Rivers National Park.

Piers is dwarfed by a grass tree of the Xanthorrhoea genus. This perennial flora is native to Australia. Their growth rate is very slow and varies among the 28 species. While a 5m-tall member of the fastest growing Xanthorrhoea species may be 200 years old, a member of a slower growing species may take three times as long to reach the same height.

Piers Thomas wades across Green Gully Creek. Most of the third day is spent walking through this creek, which can be dangerous after heavy rainfall as the water level can reach chest height in places. There is a weather station at Cedar Creek which will send out an alarm if there’s more than 40mm of rain in a day, sending a text message to Piers who will arrange an emergency helicopter to evacuate walkers if necessary. This hasn’t happened so far for any of the 90+ groups that have completed the circuit.

Piers takes a break in the gorge beside Green Gully Creek. Many thousands of years ago, this area was muddy sediment at the bottom of an ocean. Pressure and heat gradually transformed the sediment into hard rocks. Volcanic eruptions and shifting plates propelled the rocks skyward and weather and ice erosion did the rest, sculpting the gorge into a series of stark formations like the one pictured.

A group of walkers crosses a waterhole in Green Gully Creek. This is probably the most isolated part of the track, deep within a gorge system flanked by sheer and imposing rock formations. This section of the walk involves wading and bush-bashing. It’s a case of making your own path – sometimes it’s easier to battle through the stinging nettles and brambles on the bank than it is to wade through deceptively strong currents. Although this section of the walk is the shortest day at 13km, it is the most mentally demanding, as you have to think about the careful placement of each and every footstep.