Slot canyon

A slot canyon is a narrow canyon, formed by the wear of water rushing through rock. A slot canyon is significantly deeper than it is wide. Some slot canyons can measure less than 1 metre (3 ft) across at the top but drop more than 30 metres (100 ft) to the floor of the canyon.

Many slot canyons are formed in sandstone and limestone rock, although slot canyons in other rock types such as granite and basalt are possible. Even in sandstone and limestone, only a very small number of creeks will form slot canyons due to a combination of the particular characteristics of the rock and regional rainfall.

Slot canyons are found in many parts of the world, predominantly in areas with low rainfall. Some of the most well known slot canyons are to be found in the Southwestern United States. Other significant areas include the Sierra de Guara in northern Spain, the Pyrenees on the border of France and Spain, and the Blue Mountains in New South Wales, Australia.

The largest known area of slot canyons in Australia is in the Blue Mountains, west of Sydney. They occur in a narrow band of sandstone that runs roughly 30 kilometres (19 mi) from east to west, and about 100 kilometres (62 mi) from south to north. The majority of these canyons are in the Wollemi Wilderness, and are difficult to access. A small number are regularly visited by canyoners on weekends in summer. The Grand Canyon, near Blackheath, has a tourist track along its rim, but requires abseiling (rappelling) or swimming to visit fully.

Sandstone slot canyons can also be found in a few more remote parts of Australia, including Karijini National Park and the Bungle Bungles in Purnululu National Park, both in Western Australia, and Carnarvon Gorge in Queensland.

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