Gosses Bluff
Key facts
- Country
- Australia
- Diameter
- 22 km
- Age
- about 142 million years
- Location
- 23.82° S, 132.31° E
A ring of steep red sandstone hills about 5 km across, rising some 150 m above the surrounding plain, which is the eroded central uplift of a much larger crater.
Gosses Bluff rises abruptly from the flat plains of the Northern Territory, about 175 km west of Alice Springs. From a distance it looks like a single great wall of red rock; from above it is a ring of steep hills about 5 km across. To the Western Arrernte people it is Tnorala, a sacred site.
The impact. About 142 million years ago, an asteroid or comet struck the region, forming a crater that is thought to have been about 22 km wide. Since then erosion has removed roughly 2 km of rock from the landscape. The original crater rim is gone, and what we see today is the eroded central uplift, rocks that were pushed upwards from deep below the crater floor in the moments after the impact. Hard sandstone layers in this uplift resisted erosion and now form the ring of hills.
Proving an impact. Gosses Bluff was long thought by some to be a salt dome or volcanic structure. In the 1960s and early 1970s American and Australian geologists studied it in detail and found abundant shatter cones, cone-shaped fractures created by a powerful shock wave, along with shocked quartz. These established Gosses Bluff as one of the most important impact structures in Australia.
Tnorala. Gosses Bluff is part of the Tnorala Conservation Reserve, managed jointly with its Traditional Owners. In Western Arrernte tradition, Tnorala was formed in the Dreaming, when a group of women danced across the sky as stars in the Milky Way. During the dance a baby, in a wooden carrier, fell to Earth, and the carrier struck the ground with such force that it pushed up the rocks to form the ring we see today. The story is a striking parallel to the scientific account of something falling from the sky.
Visiting. A track leads into the centre of the ring, where there is a picnic area and a short walk. A lookout on the outer side gives a fine view of the structure. Climbing on the bluff itself is not permitted, out of respect for its cultural significance. A four-wheel-drive vehicle is recommended, and a permit is needed to continue along the Mereenie Loop road towards Kings Canyon. Removing rocks is not allowed.
Why it matters. Gosses Bluff is one of the best-exposed examples in the world of the central uplift of a complex crater. Because erosion has cut down into it, geologists can study the rocks that once lay beneath a crater floor, much as they do on a far grander scale at Vredefort.
Did you know?
The ring of hills is the eroded central uplift of a crater once about 22 km across.
In Western Arrernte tradition, Tnorala was formed when a baby's wooden carrier fell from the sky.
Erosion has removed about 2 km of rock since the impact.