Gunlom is located in the Kakadu National Park Kakadu covers almost 20,000 square kilometres and is a place of enormous ecological and biological diversity. It extends from the coast and estuaries in the north through floodplains, billabongs and lowlands to rocky ridges and stone country in the south. These landscapes are home to a range of rare and endemic plants and animals, including more than one-third of Australia's bird species and one-quarter of its freshwater and estuarine fish species.
Gunlom is part of Waterfall Creek, one of the major tributaries of the upper South Alligator River. This is the only large tropical river system in the world to be entirely protected within a national park and a World Heritage Area
The Gunlom Falls is a cascading waterfall. The falls descend from an elevation of 168 metres (551 ft) above sea level and range in height between 60–85 metres (197–279 ft)
There are six main landforms in Kakadu National Park: the Arnhem Land plateau and escarpment complex, known as the stone country; the outliers; the lowlands; the southern hills and basins; the floodplains; and the tidal flats. Each landform has its own range of habitats. Kakadu’s varied landscapes and the habitats they contain are features that contributed to its listing as a World Heritage Area.
Most of Kakadu was under a shallow sea approximately 140 million years ago, with the escarpment wall formed from sea cliffs and Arnhem Land from a flat plateau above the sea. Currently the escarpment rises 330 metres above the plateau and extends approximately 500 kilometres along the East edge of the park and on into Arnhem Land.
Geologists consider that Kakadu's landscape reflects the geological history of the region. Rocks of different types and ages determine topographical and soil characteristics. Northern Kakadu is quite different to Southern Kakadu. The oldest rock formations in the Park are a mixture of sedimentary rock, laid down in a large geological depression called the Pine Creek Geosyncline, and igneous or volcanic rocks. They date from about 2500 million years ago, about half the age of the earth. The layered sequence of sedimentary and volcanic rock was changed under conditions of extreme heat and pressure into schist, gneiss, quartzite and marble. This was part of a major mountain building event, the Top End Orogeny, about 1800 million years ago.
About 140 million years ago, during the Mesozoic era, a shallow sea spread across most of Kakadu from the north. The escarpment and outliers were sea cliffs at the edge of a vast, shallow sea. About 100 million years ago the seas receded. The rate of retreat of the escarpment at its weakest points has been estimated at about 1 metre every 1,000 years. The sandstone is strongly armoured by a layer of iron and silica. As water seeps through the rock the water 'takes' these minerals with it and then deposits them on the surface of the rock, forming a tougher rock face. Where this occurs the rate of retreat of the escarpment is much slower.
Silica
Q1 Describe the colours of the waterfall rock escarpment from WP1 at the lower swimming hole? What is the flow of the waterfall like when you visited?
Q2 Describe the texture and colours of the rocks at the edge of a pools at the top of the waterfall?
Q3 What type of waterfall is this? (read notes)
*Please note* Check conditions before attempting this earth cache. It might not always be available due to weather conditions (eg. Wet Season in the NT). The climb to the top will not suit all people. Please be careful and take water with you. Its not a long walk, but a tough one.
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