Kakadu National Park

Some rocks in Kakadu are very, very old. They are older than the dinosaurs!

Long ago, the sea came in. The big cliffs were once sea cliffs. Now rivers spread mud over the flat land below.

Kakadu has some of the oldest rocks on Earth's surface, about 2,500 million years old, Parks Australia says. The park's great cliff, the escarpment, is made of sandstone. One of its rock layers, the Kombolgie Sandstone, was laid down by a huge river about 1,700 million years ago, and you can still find ripple marks from that river in the rock.

About 140 million years ago, a shallow sea covered much of Kakadu. The escarpment was its shoreline: sea cliffs with flat land above. Today the escarpment rises to 330 meters above the plains and runs for more than 500 kilometers. Below it, the floodplains are young land, built up by sand and silt that wet-season floods carry down from the rocks.

Parks Australia dates Kakadu's oldest exposed rocks to about 2,500 million years, including volcanic rocks in the Southern Hills and Basins; at the Budjmi lookout near Twin Falls, 1,800-million-year-old granite is overlain by Kombolgie Sandstone, an unconformity representing a 100-million-year gap. The Kombolgie Sandstone itself was deposited by a huge river about 1,700 million years ago and preserves ripple marks and cross-bedding.

About 140 million years ago much of the region lay under a shallow sea; the escarpment formed its sea cliffs and the Arnhem Land plateau the land above. The escarpment now rises up to 330 m and extends over 500 km along the park's eastern boundary, eroding in places by up to a meter every thousand years, with isolated outliers that were once islands (Britannica). UNESCO contrasts this ancient stone country with floodplains that are recent, dynamic landscapes shaped by changing sea levels and big wet-season floods.

Most people say the north of Australia has two seasons: wet and dry.

Kakadu's Aboriginal people know six seasons. Each one has its own weather, plants and animals.

Many people describe northern Australia as having a dry season, from April to October, and a wet season, from November to March. Kakadu's Traditional Owners recognize six seasons, based on thousands of years of knowing the land.

In Kudjewk, the monsoon season, storms bring heavy rain and floods, and spear grass grows over two meters tall. Bangkerreng brings "knock 'em down" storms that flatten the grass. Yekke is cooler, with misty mornings and water lilies on the wetlands. Wurrkeng is the cold time, when the floodplains dry out. Kurrung is hot and dry. Then Kunumeleng, the pre-monsoon season, brings afternoon thunderstorms again.

Parks Australia explains that the Traditional Owners recognize six seasons, marked by subtle shifts in weather, the plants in flower and the bush foods most abundant: Kudjewk (monsoon), Bangkerreng ("knock 'em down" storms), Yekke (cooler, with less humidity), Wurrkeng (cold weather, with days around 30 °C and nights about 17 °C), Kurrung (hot, dry weather) and Kunumeleng (pre-monsoon storms).

Each season changes the land. In Kudjewk floods drive goannas, snakes and rats into the trees and magpie geese nest in the wetlands; in Yekke and Wurrkeng Bininj/Mungguy begin patch burning to "clean the Country" and encourage new growth; in Kurrung sea turtles nest on the beaches of Field Island and West Alligator Head; in Kunumeleng barramundi move to the estuaries to breed. Some areas of the park are closed by flooding during the wet.

Aboriginal people have lived in Kakadu for a very, very long time.

Their families still live here today. They care for the land, the plants and the animals. Visitors can learn from them.

Kakadu has been home to Aboriginal people for an extremely long time: more than 50,000 years, UNESCO says, and more than 65,000 years, according to Parks Australia. Britannica explains that digs have shown it was one of the earliest places where people settled in Australia.

Today about 19 clan groups share the land. Each clan is two or more families who own an area of land together, passed down from one generation to the next. Caring for the land and its wildlife is a big part of their culture. Kakadu became a national park in 1979. Today it is run jointly by its Traditional Owners and the Australian Government, and a majority of its board represents the Traditional Owners.

UNESCO states that Kakadu has been home to Aboriginal people for more than 50,000 years; Parks Australia, writing with the Traditional Owners, gives more than 65,000 years. UNESCO emphasizes that the hunting-and-gathering tradition seen in the art and archaeological record is a living tradition that continues today, which it describes as rare among hunting-and-gathering societies.

Parks Australia explains that Aboriginal people are called Bininj in the north of the park and Mungguy in the south; there are about 19 clan groups, each of two or more family groups sharing ownership of an area of land, with boundaries usually passed down through the father. A kinship system divides people, plants, animals and land into two moieties, Duwa and Yirridja, each with eight skin groups. Joint management, UNESCO says, is an essential part of how the park is protected.

People painted on the rocks in Kakadu long, long ago.

The paintings show animals, people and things they used. Many are red. Some even show the bones inside animals!

Kakadu has one of the world's greatest collections of rock art. Britannica says about 5,000 sites have been found, and archaeologists think there may be up to 15,000. Some paintings are up to 20,000 years old, which makes them one of the longest records of any group of people on Earth, Parks Australia says.

The main galleries visitors can see are at Ubirr and Burrungkuy (Nourlangie). Look for animals painted to look real, "x-ray" paintings that show the bones and insides of animals, and paintings of early contact with European people. Painters crushed colored rocks on a stone and mixed them with water, using brushes of hair, reeds, feathers or chewed sticks.

Britannica reports some 5,000 identified rock art sites and archaeologists' estimates of up to 15,000, mostly on the escarpment and in gorges, some up to 20,000 years old. UNESCO recognizes the art under criterion (i) for its range of styles, density of sites and detailed depiction of human figures and identifiable animals, including long-extinct species, and under criterion (vi) as evidence of social life from the Pleistocene to the present.

Parks Australia notes that for Bininj/Mungguy the act of painting was generally more important than the painting itself, so older works are often painted over. Pigments were ground on stone palettes and mixed with water; hand stencils were made by blowing wet pigment around a hand. Haematite, a reddish iron oxide, lasts longest, which is why most old paintings are red. Painting continues today, mostly on bark, paper and canvas. Conservation work protects the art from weathering, water, mud-building wasps, termites, feral animals and people (UNESCO).

Kakadu is wild, so be careful.

Crocodiles live in the water, so never swim in rivers or wetlands. Drink lots of water and wear a hat. Ask before you take a photo of people.

Saltwater crocodiles live in most of Kakadu's waters, from floodplains and billabongs to creeks, rivers and the coast. Parks Australia warns that they hide underwater and can attack in knee-deep water, so even wading can be dangerous. Stay on marked tracks and obey warning signs; Parks Australia says the safest place to swim is a public or hotel pool.

It is also very hot: temperatures often reach 30 °C and can pass 40 °C in summer. Walk in the cooler parts of the day, wear a broad-brimmed hat and sunscreen, and carry plenty of water. Respect the culture too: ask permission before photographing Bininj/Mungguy, and never enter restricted areas.

Parks Australia's "Crocwise" advice: saltwater crocodiles inhabit most waters in the park and are ambush predators that may stay hidden for long periods; assume they are present even without signs, camp at least 2 m above the high-water mark and 50 m from the water's edge, and do chores at least 50 m from the water. Waterways can also flood suddenly, rock pools are slippery and cold water can cause shock.

Heat is the other major hazard: temperatures regularly exceed 30 °C and can pass 40 °C, with risks of heat exhaustion, dehydration and hyponatremia. Walk only in the cooler hours, avoiding 2:30 to 6:30 p.m. (in summer, not after 11 a.m.), and obey rangers and road closures. Culturally, visitors should not photograph people without permission and should keep out of restricted areas, which may be ceremonial sites, burial grounds or homes.