In this episode participants of the virtual excursion will form an idea about what makes the Willandra Lakes area, including Lake Mungo, so distictive. They will see how the lakes environment has been shaped and the natural changes that have occurred over many hundreds of years. Students will see visuals to match geographic terminology.
Landscape formation (2:03)
Episode 5 – Landscape formation
Warning – Aboriginal and Torres Strait Islander viewers are warned that the following video may contain images and voices of deceased persons.
(gentle music)
[Screen reads: Question? What makes the Willandra Lakes and Lake Mungo landscape unique?]
Narrator: Melissa
The region contains a system of Pleistocene lakes formed over the last two million years. These lakes are now dry. There are five large, interconnected dry lake basins and 14 smaller basins.
Today the lake beds are flat plains vegetated by salt-tolerant low bushes and grasses. Most of the Willandra Lakes are fringed on the eastern side by crescent-shaped dunes referred to as lunette that was created by layers of sediment being deposited between 40,000 and 15,000 years ago.
The original sources for the lakes was a creek flowing from the Eastern Highlands to the Murray River. When the Willandra Billabong Creek ceased to replenish the lakes, they dried in a series of south to northwest over a period of several thousands of years, becoming more progressively saline.
[Screen reads: Fact. Saline soils are soils with a high concentration of salt]
The ancient shoreline is stratified into three major layers of sediment that were deposited at different stages in the lake's history.
[Screen reads: Fact. Stratified soil is arranged into different layers called strata]
The earliest sediments are more than 50,000 years old and are orange red in colour. Above are clays, clean quartz sand, and soil that were deposited along the lakes' edges when the lakes were full.
The top layer is composed largely of windblown clay particles heaped up on the lunettes during periods of fluctuating water levels before the lakes finally dried up.
[Screen reads: Fact. Glaciated means covered or having been covered by glaciers or ice]
The Willandra Lakes Region is particularly important because it has not been glaciated whereas sediments in other regions have been removed by glacial processes. Here they have remained undisturbed for many thousands of years.
(gentle music)
List of sources and acknowledgements
Image: Willandra Lakes Region formation. Source image retrieved from www.geosciencesaustralia.com
Image: Willandra Lakes Region lake names. Source image retrieved from www.geosciencesaustralia.com
Image: Willandra Lakes water sources. Source image retrieved from www.geosciencesaustralia.com
Video: 45,000 years at Lake Mungo. Provided by National Parks and Wildlife www.visitmungo.com.au
Image: Section of three major sediment layers. Source provided by Professor Jim Bowler.
Narration. Voice over by Melissa Ellis, Southern Cross School of Distance Education.
Credits
NSW Government Public Schools, Learning Systems, DART connections, Southern Cross School of Education. Virtual Excursions 2017.
[End of transcript]