The Breadknife is a dyke

Dike (geology)

A dike or dyke in geology is a type of sheet intrusion referring to any geologic body that cuts discordantly across* planar wall rock structures, such as bedding or foliation...

 located in New South Wales

New South Wales

New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...

, Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. The dyke is nearly 850 metres high, but often is only 500 m wide, which is particularly rare. The Breadknife was part of a large shield volcano

Shield volcano

A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. They are named for their large size and low profile, resembling a warrior's shield. This is caused by the highly fluid lava they erupt, which travels farther than lava erupted from more explosive volcanoes...

, that first erupted about 18 million years ago and stopped about 15 million years ago. This shield volcano rose about 1,000 m and is now largely eroded, forming the Warrumbungles

Warrumbungles

The Warrumbungles is the name of a mountain range and National Park located in northern New South Wales, Australia. The nearest town to the Warrumbungles is Coonabarabran...

. The breadknife was formed when hot magma spread through a soft rock. When the magma solidified and became harder than the soft rock, erosion exposed a beautiful dyke.

A network of walking tracks are used to access the steep mountains and ridges surrounding the dyke. Nearby volcanic remnants include the Belgourie Spire, Belgourie Split Rock, Crater Bluff, Bluff Mountain and Mount Exmouth. The shortest walk completely around the Breadknife is hard and steep, taking roughly five hours to complete.