A quick guide to Eurobodalla’s geological sites

The Eurobodalla region is home to a world-class gallery of geological sites hundreds of millions of years in the making. From north to south, here are nine incredible formations to seek out.

Wasp Head, South Durras

The golden sandstone cliffs at Wasp Head, which forms part of Murramarang National Park, form the exposed southern edge of the 280-million-year-old Sydney Basin. Look for the honeycomb weathering of the eroded sandstone on the northern side of the head, and the ironstone box work (iron-rich sediment that has been formed into a box-like pattern) on the southern side. You’ll also see clusters of shellfish fossils embedded in the rocks, as well as boulders of petrified magma (now basalt).

Park at the Wasp Head car park and take the 2km-return Wasp Head walking track. At low tide, you can walk right around the head.

Myrtle Beach, South Durras

Just south of Wasp Head, two worlds collide at Myrtle Beach where the sandstone cliffs of the Sydney Basin come to an end and rise up to meet the much older Wagonga Ordovician rocks of the Lachlan Fold Belt. The point where two major geological units meet is called an unconformity and this unconformity is strikingly revealed in the cliff face at the northern-to-middle section of the beach.

From the Myrtle Beach car park, it’s a 60m-return walk through an enchanting spotted gum forest (also part of Murramarang National Park) to the beach.

Guerilla Bay

Dating back some 510 million years, the unusual rock formations surrounding Guerilla Bay were thought to have been formed during an interval of subduction, when tectonic plates overlap, and the high temperatures and pressures associated with this process converts seabed sediment to rock. Squeezed, bent and broken after they formed, possibly as a result of compressive movement within the ancient subduction zone, the rocks around Guerilla Bay now consist of a mix of fragments called tectonic melange.

There’s a small car park on Burri Burri Road, which is the starting point for the Banksia Walk, a 1.5km-return walk to Burrewarra Point.

 
Bendethera Caves

Deep in Deua National Park, the Bendethera Caves is a karst limestone cave system reached via a challenging 8km-return walking trail from Bendethera Valley campground, 57km (1 hour 45 minutes’ drive) west from Moruya.

Along the way, look out for the interpretative signs pointing to dolines, which are circular bowl-shaped depressions in the limestone formed by water dissolving the calcium carbonate over time.

The cave system, which is thought to be between 440 and 415 years old, is over 250m long, 320m wide and contains massive limestone formations in caverns with up to 15m-high ceilings. Bring a torch!

 
Bingie Bingie Point, Bingie

At the northern end of Bingie Beach, Bingie Bingie Point is a site of intense interest to geologists because of the spectacular display of intrusive igneous rocks (particularly granite and gabroic diorite) on the northern side of the point.

Intrusive rock bodies are masses of magma which have cooled and crystallized below the earth’s surface as opposed to having been formed from a volcanic eruption and cooled on the surface. Part of the early Devonian granites of the Moruya batholith, the Bingie Bingie Point rocks are between 415 and 390 million years old.

Bingie Bingie Point also lies on the Bingie Dreaming Track, a 13.5km coastal path used by the Brinja-Yuin people that traces an ancient Song Line stretching from Congo in the north to Tuross Head in the south. There’s a carpark at both ends.

 
Montague Island

Nine kilometres offshore from Narooma, the wildlife paradise of Montague Island was part of the mainland until about 9,000 years ago. But the island itself, which is home to the largest fur seal colony in NSW, is much older, with the northern part of the island made up of an andesite lava extrusion from a volcanic eruption on Gulaga (formerly Mount Dromedary) about 95 million years ago.

The dark-coloured rocks in the north contrast with the southern part of the island which has been formed through intrusive igneous rocks that have cooled underneath the surface and been exposed through erosion. These igneous intrusions in the south of the island now take the shape of impressive sculptural tors that have been rounded and smoothed by weathering.

There are several options for touring the island.

 
Glasshouse Rocks and Australia Rock, Narooma

Narooma’s Surf Beach is home to two sites of geological significance and beauty found at either end of the beach. One of the most photographed spots on the Eurobodalla coastline, Glasshouse Rocks lies at the southern end.

Made from a mix of sedimentary chert and shale and thought to be up to 440 million years old, the rocks are known for their chevron folds, where the sedimentary layers have been squeezed into spectacular zig zag patterns.

At the northern end of Surf Beach you’ll find a display of igneous pillow lava, which was formed by the lava flow of a submarine volcano or hot spot in the ancient Pacific Ocean. Here you’ll also find Australia Rock: another photographer’s dream and freak of nature formed from the remnants of volcanic activity hundreds of millions of years ago.

 
Mystery Bay Kink Zone

Named for a geologist and his small expedition party who went missing in the area without a trace in 1880, Mystery Bay’s dramatic landscape inspires locals and tourists to ponder the mysterious nature of the place itself. Dating back nearly 500 million years to the Ordovician period, the rocky outcrops seen just offshore lie in what is known as a kink zone, which means they’ve been subjected to great pressure during the moving of tectonic plates.

A feature called foliation is apparent in the kinks and breaks in the angular brittle rocks, which makes these rocks look as if they could have been pieced together one by one.

There is car parking at the northern and southern ends of the beach.

 
Gulaga, Tilba Tilba

Rising up above the charming hinterland villages of Tilba, the dramatic mountain known as Gulaga is the inner core of an ancient volcano that last erupted around 65 million years ago.

Like the mountain itself, the magnificent granite tors near its summit have deep spiritual and cultural significance to the Yuin people.

You can climb the mountain yourself (allow four to five hours for the return slog from La Galette in Tilba Tilba, where you can leave your car), but to learn more about its cultural significance, sign up for a guided hike run by local Aboriginal-owned organisation Ngaran Ngaran Cultural Awareness.