Australia: The Land Where Time Began

A biography of the Australian continent 

The Kimberley Group                                          

The Kimberley Group are a number of  ranges of Precambrian  rocks, greater than 2 billion years old, that form the Kimberley Plateau that is an exotic terrane which collided with other blocks that formed the original landmass of Australia. It had an independent drainage system that it has maintained. It is surrounded by rocks of the Halls Creek Belt assemblage which are between 2 and 1.75 billion years old. The oldest planated surface has been called the High Kimberley Surface. The surrounding younger, usually duricrust, surface is called the Lower Kimberley Surface. The Kimberley Block is surrounded by a raised feature called the Kimberley Rim, which is the main reason the drainage of the block is isolated from the surrounding areas. The Fitzroy is the only river that breaches the Kimberley Rim

The Kimberley Plateau rose above the sea about 2400-1800 million years ago. It has remained dry land ever since, though about 600 million years ago it was an island, and several times it has been a peninsula. About 350 million years ago it was surrounded by a barrier reef like the present-day one along the Queensland coast. The block was uplifted and tilted to the north-west between 3 and 7 million years ago. This was the last time the block has undergone any substantial movement. 

The Northern part of Australia, including the Kimberleys, is now in the tropics as a result of the northerly progress of the continent, bringing it under the influence of the tropical monsoon. During the summer, "The Wet", the monsoon drops enormous amounts of rain on the area and this, together with the very resistant types of rock, means the soils over most of the Kimberleys away from flood plains and estuaries are very thin. The "Wet" is soon followed by the "Dry", when the lush vegetation is desiccated by the blazing sun and dry air. Because of the extremes of climate experienced in the area the Kimberleys have evolved a number of plant species, many unique to the area, which can survive both flood and drought. The most prominent of the unique species is Adansonia gregorii, the boab, or baobab, the bottle tree endemic to the region, whose closest relatives are found in India, Africa and Madagascar. 

Tidal Waterfalls

The scenery along the coast of the Kimberleys can be spectacular, and none more so than the cliffs where the 10 m-tides rush through narrow gaps in the cliffs. This occurs at several places, but the most impressive place is at Talbot Bay, north of King Sound. The tides near the coast cause the water to swirl around the many small islands and submerged rocks at speeds not seen around other parts of Australia and where it surges through the narrow gaps, as in the narrow 70-m gorge between the cliffs, it does so with such force that it forms what appears to be a horizontal waterfall. The effect is accentuated by the entrance of the gorge being much wider then the main part of the gorge so that the water is funnelled into a very narrow space between the cliffs, hence the water is forced high above the level it would be at if the it wasn't squeezed by the cliffs. 

At Talbot Bay there is also an inner gap and a second horizontal waterfall, narrower than the outer gorge, where the raging torrent is even more spectacular than the outer one. The inner gorge is 100 m long and the water has been estimated to roar through the gorge at 20-30 km/hr. The roar continues for nearly the whole day because the same spectacle is repeated in reverse when the tide goes out. The roar drops to a gurgle for 2-3 minutes before the change of tide, then there is silence for 1 minute before the gurgle signals the change of tide and the roar begins again. There is no where else that has such spectacular tides. At places like Hangchow in China the incoming tides move up the river as a wall of water, but nowhere is there such a spectacle as along the coast of the Kimberleys. 

The Kimberleys area is very hard to travel in for some of the year. The sea approach is hazardous because of the many uncharted rocks and reefs near the coast. The country is very rugged and difficult to cross in places and in the Wet so much water is dumped on it the the rivers become raging torrents. 

The Kimberleys Region

The Kimberley region is fringed by the Indian Ocean and the Timor Sea to the north and west, the Great Sandy Desert to the south, Tanami Desert to the southeast and the Northern Territory border to the east. The region covers approximately 423,000 km2, making it almost twice the size of the state of Victoria. It includes four Local Government Areas: Shire of Broome, Shire of Derby/West Kimberley, Shire of Halls Creek and the Shire of Wyndham-East Kimberley.

The major towns in the Kimberley region are Broome, Kununurra, Derby, Halls Creek, Wyndham and Fitzroy Crossing. These towns are important support and service centres for the many smaller communities that surround them. The largest town in the Kimberley is Halls Creek or you can make Derby, 220 km away at the mouth of the Fitzroy River as your base for travelling into the area.

This northern-most region of Western Australia, the Kimberley offers a rugged adventure to a remote area of rivers and magnificent landscape. Here you can find red soil, rocks, gum trees and blue skies. Immerse yourselves in the spectacular gorges on the Fitzroy River, Wolfe Creek meteorite crater, the Gibb River Road and Bungle Bungle National Park. Enjoy the company of freshwater crocodiles, wallaroos and the rare black-footed wallaby.

The Kimberley region enjoys a climate broadly divided to 'dry' and 'wet' seasons. The most popular period to visit is between April and September, but there is nothing like being there in the Wet (the rainy season in the north), which offers ethereal thunderstorms, although rains make many watercourses impassable. The dry season presents warm and balmy, tropical, idyllic conditions enjoyed by residents and increasing numbers of visitors. The tropical summer season or 'wet' includes variable weather systems ranging from longer hot and dry periods to monsoonal rains and tropical storms.

Sources & Further reading

  1. Running Down, Water in a Changing Land, Mary White, Kangaroo Press, 2000
  2. Hellen Grasswill & Reg Morrison, Australia, a Timeless Grandeur, Lansdowne, 1981


Author: M. H. Monroe
Last updated 27/03/2011



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