Tnorala (Gosse Bluff)

Tnorala, better known as Gosse Bluff, is a ring of ridges rising about 180 metres out of the flat country west of Alice Springs, roughly five kilometres across and almost perfectly circular. From a distance it looks like a range of hills that has closed in on itself; from inside, the walls surround a sheltered, open basin. It is what remains of a cosmic collision: an asteroid or comet struck here about 142.5 million years ago, close to the boundary between the Jurassic and Cretaceous periods, and blasted out a crater estimated at around 22 km across.

That original crater has long since worn away. The ring visible today is the central uplift, the rock that rebounded upward at the moment of impact and has proved harder than the ground around it, so erosion has left it standing proud. Its impact origin was proposed in the 1960s, and the strongest evidence came from the shatter cones, the distinctive striated cone-shaped fractures that form in rock only under extreme shock pressure, which are abundant here. Two abandoned oil exploration wells near the centre are a reminder that geologists once saw the structure as a possible petroleum trap.

To the Western Arrernte people Tnorala is a sacred place, and it lies within the Tnorala Conservation Reserve. Their account of its origin is itself a story of something falling from the sky: in the Dreaming, a group of women were dancing as stars in the Milky Way, and one of them, growing tired, set her baby down in a wooden carrier, a turna. The carrier toppled over the edge of the sky and struck the earth, driving the rocks up into the circular range. The baby's parents, the evening and morning stars, still search for it, and the turna can be seen in the night sky as the constellation Corona Australis.

The European name comes from the explorer Ernest Giles, who in 1872 named the bluff after Henry Gosse, brother of the surveyor William Gosse. The best way to grasp the shape is from above: a short walk leads to a lookout on a ridge with views into the crater, a longer loop climbs higher still, and on the approach the Tylers Pass lookout shows the whole ring standing out of the plain. Inside the ring there is a small picnic area with shade and information about the site.

Getting there

Tnorala lies about 175 km west of Alice Springs, in the West MacDonnell region of the Northern Territory, reached by Larapinta Drive or Namatjira Drive. The roads are sealed as far as the turn-off, but the last 10 km into the reserve require a four-wheel-drive vehicle. The nearest airport is Alice Springs Airport (ASP). The cooler months from April to September are the most comfortable time for walking here.