It’s National Aborigines and Islanders Day Observance Committee (NAIDOC) week. What better time to celebrate a shared research project between the Wajarri people and the University of Western Australia!
Australia’s largest Aboriginal ochre mine is Wilgie Mia. In Wajarri Yamatji country far north of Perth, it is an incredibly important cultural heritage site. Red, yellow and green ochres from the mine have been traded across the country for many thousands of years.
It’s said that ochre from Wilgie Mia was traded across Western Australia into the Kimberley, the Pilbara, down to the south coast and into neighbouring states. Red and yellow ochres are still an important part of Indigenous Australian cultures today.
This week, three young Wajarri men are visiting the University of Western Australia to work alongside archeologist Vicky Winton. Together, they are studying samples from several new sites near Wilgie Mia.
“We’ll be going down to the stores and floating some of the samples,” says Vicky. “That’s a technique that involves putting excavated sediments into water.” Lighter material, such as burnt or charred wood, separates from rocks and makes it easier to sort.
Even after it has been burnt, charred wood can reveal interesting things. Using a technique developed in Europe, the team previously identified the species of tree burnt in fires long ago.
“When the conditions are right, the wood chars and details of the anatomical structure are preserved intact,” says Vicky. Archeological samples can be compared to modern charcoal, taken from partially burnt trees that have been carefully identified. Brendan Hamlett, a Wajarri Traditional Owner who worked on an earlier trip to the University, was surprised to find Mulga trees had been burnt the past. Today, the Wajarri people mainly use Miniritchie and Gidgee trees, he says.
High-end technology can be used to study rich cultural treasures. Recently, a super computer from the University of Western Australia stitched photos of cave shelters into 3D models. Having a digital record of the sites makes it easier to spot any damage that might occur in the future.
By sharing knowledge, everyone benefits. Training the next generation is a priority for the Wajarri Traditional Owners, says Brendan. “This is the first time I’ve made maps with a computer. It’s unreal to use this technology to draw parts of my country.”
Brendan Hamlett and Liam Bell sort samples in the archeology lab at the University of Western Australia. Image: Annie Carson
Quiz questions
What word is given to the process by which tadpoles turn into frogs?
True or false? Earth’s internal heat comes partly from radioactive decay?
Which sugar-based chemical makes the exoskeletons of crustaceans strong? Is it a) chitin, b) glucose or c) starch?
How many moons do Mercury and Venus have, combined?
Which famous physicist said, "If quantum mechanics hasn’t profoundly shocked you, you haven’t understood it yet."
Video game challenge
The first ever Australian STEM Video Game Challenge is taking place this year!
Open to students in Years 5–12, entrants are encouraged to design, build and submit an original video game around the theme of STEM, that's science, technology, engineering or maths.
Students can enter individually or in teams, and have the opportunity to win fantastic prizes, including attending an awards ceremony at PAX AUS – Australia’s biggest gaming convention.
It’s completely free to enter, links to software and tools are provided – all that’s needed is imagination and a great idea for a game! For more information, and to register, please visit www.stemgames.org.au
Try this: Flotation separation
You'll need these things.
Pour the cereal into a container of water and stir well.
Let it sit for two minutes, then use the sieve to gently scoop out the cereal ingredients floating on top of the water.
Shake the contents of the sieve onto a piece of paper.
After you have collected all the floating cereal ingredients, pour the water and the rest of the ingredients through the sieve.
Put the cereal ingredients that sink on a separate piece of paper. Compare the ingredients that float to the ones that sink!
You will need
Cereal that contains a mixture of puffed wheat or puffed rice, flakes and fruits
Measuring cup
Large container
Water
Spoon
Sieve
Two pieces of paper
Sink
What to do
It’s best to do this activity in a kitchen, next to the sink.
Put enough water in the container to make it about three-quarters full.
Measure out one cup of cereal.
Add the cereal to the container of water.
Stir the cereal for 30 seconds with the spoon.
Leave for two minutes, while some of the cereal settles to the bottom.
Look at the container to see which cereal ingredients have floated to the top, and which have fallen to the bottom.
Using the sieve, gently scoop out the cereal ingredients floating on top of the water. Shake them onto a piece of paper.
Once you have collected all the ingredients floating on top of the water, take the container to the sink.
Slowly pour the water in the container, along with the cereal ingredients at the bottom, through the sieve so the sieve catches the cereal ingredients.
Shake the cereal ingredients from the sieve onto a different piece of paper.
Compare the two samples. Which ingredients floated to the top, and which fell to the bottom?
What’s happening?
When we did this activity, the puffed rice, puffed wheat and corn flakes floated to the top, while the sultanas, bran flakes and nuts fell to the bottom.
This is an example of flotation separation, a method to separate a mixture into its ingredients, or components, based on whether they float or not. Objects float if they are less dense than water, which means they weigh less than an equal volume of water. Density is equal to mass divided by volume.
Applications
Flotation separation is used in archeology to separate small, delicate material. Seeds and charcoal tend to float, while stone tools sink. After separating by flotation, the material can be sorted by hand. A magnifying glass and tweezers help to sort very small materials.
Watch it! The chemistry of baking, presented by A Week in Science by the RiAus.
Quiz answers
Metamorphosis is the process in which tadpoles turn into frogs.
True. Radiation is a source of the Earth’s internal heat.
a) Chitin makes the exoskeletons of insects and crustaceans strong.
None, neither Mercury nor Venus have any moons.
Niels Bohr.
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