Lawn Hill
Key facts
- Country
- Australia
- Diameter
- 18 km
- Age
- about 470 million years
- Location
- 18.67° S, 138.65° E
A ring of low limestone hills about 18 km across in north-western Queensland, near Boodjamulla (Lawn Hill) National Park.
Lawn Hill is an eroded impact structure about 18 km across in north-western Queensland, Australia, near Boodjamulla (Lawn Hill) National Park and the large Century zinc mine.
What can be seen. The structure is marked by a ring of low hills made of limestone, which filled the crater after the impact, surrounding a central area of disturbed Proterozoic rocks.
What it hit. The impactor struck Proterozoic sedimentary rocks, about 1.6 billion years old, which were covered at the time by younger Cambrian sediments and a shallow sea.
Proof of impact. Geologists found shatter cones, cone-shaped fractures produced by shock, and quartz grains with planar deformation features, which confirmed an impact.
Age. The impact happened in the Ordovician, about 470 million years ago, based on the ages of the rocks affected and those that filled the crater.
Why it matters. Lawn Hill is a well-preserved example of a crater in a region of ancient rocks, and its proximity to a major ore deposit has made its geology well known. The impactor is unknown.
Visiting. The national park is open to visitors, with gorges, walking tracks and camping. Do not collect rocks in the park.
Did you know?
Lawn Hill lies near the Century zinc mine, once one of the world's largest.
A ring of limestone hills marks the crater.
It formed in the Ordovician, about 470 million years ago.