Twenty-odd million years ago, a huge shield volcano stood where the Tweed valley is now, on what became the border between New South Wales and Queensland. Erosion has since carved out its centre, leaving one of the largest erosion calderas in the world, a vast bowl of green farmland ringed by cliffs and ridges, with the volcano's old central plug, Wollumbin, also known as Mount Warning, standing in the middle. Limpinwood Nature Reserve, on the northern rim of the caldera, protects a stretch of subtropical rainforest that is part of the Gondwana Rainforests of Australia, a UNESCO World Heritage Site preserving forests whose lineage goes back to the ancient supercontinent.
The forest is dense and lush, with strangler figs, palms, tree ferns and towering brush box trees. It is home to rare birds such as Albert's lyrebird, a master mimic that can imitate the songs of other birds, and the Coxen's fig parrot, as well as pademelons, small wallabies that feed at the forest edge at dusk. Wollumbin has deep cultural significance for the Bundjalung people, and the summit track is closed to climbers out of respect and for safety.
The riding here is some of the best in the region. The roads that wind through the Tweed valley and up into the ranges, such as the road to Tyalgum and the route through the Numinbah valley into Queensland, are full of tight curves and steep climbs, with views of the caldera and the cliffs. The surface can be rough in places, and landslides sometimes close roads after heavy rain, which can be intense in summer. Watch for wildlife on the roads, especially at dawn and dusk, and cattle on unfenced sections.
Murwillumbah, about twenty-one kilometres away, is a country town of seven thousand with fuel, supermarkets and a good regional art gallery. Smaller villages like Tyalgum and Uki have cafés, pubs and general stores, often with good coffee and local produce. The area grows macadamias, avocados and tropical fruit, so look for roadside stalls. Carry water and sunscreen, and be ready for sudden storms in the afternoon during the wet season.