Welcome to the detective laboratory where we investigate ‘cold cases’ — unresolved
cases from the past.

We have an interesting case for you. We have found the remains of two people. You will need to look at the nine files of evidence and work out what happened to them. You can then submit a Cold Case Report.

Good luck with your investigation.

Evidence file 1

Location map

The remains were recovered from a now-dry lake system at Lake Mungo, in western New South Wales. The nearest major modern settlements are several hundred kilometres away.

‘Lunettes’ are sand hills like this:

Evidence file 2

Soil report

The soil near the body showed traces of vegetation, fish bones and crustacean shells from a variety of fresh water species; a variety of native mammals, reptiles and birds; and ash from cooking fires. The fish and animals whose bones were found cannot live in the area today because the environment has changed.

Evidence file 3

Body 1

The bones had been crushed, burned, crushed again, burned again and finally buried. They were only found because the topsoil had eroded and winds had exposed them at the surface. They were the remains of a young woman, aged about 18 when she died. No cause of death could be determined.

Evidence file 4

Body 2

This body had been buried intact. It was a man who was about 50 years old when he died. He was buried neatly, with a deposit of ochre, often used in ceremonies, spread over his chest. In one arm the bones had been worn down. This would have caused the man great pain from arthritis. This wearing was consistent with what would happen if he was throwing something regularly over a long period of time.

Evidence file 5

The scene of the discovery

This is what the area is like today

Evidence file 6

Ochre report

This is a piece of ochre. It is soft rock with colouring caused by the minerals in it. It can easily be crushed and made into a powder. Naturally-occurring ochre is not found in the area. The nearest deposit is several hundred kilometres away.

Evidence file 7

Dating report

The human and animal bones, and all natural materials, have been tested by a radiocarbon dating process. This process analyses the amount of carbon in the remains. By knowing the amount of carbon in that material when it has formed and the rate at which it decays, we can work out how much carbon remains and therefore how old the object is. The scientific dating process gave an age of about 40,000 years for the human and surrounding animal remains.

Evidence file 8

Stratigraphy

‘Stratigraphy’ means studying layers.

The surface of the earth is constantly changing. Wind and rain cause erosion and the movement of soil. Over time what used to be the surface gets covered over by a new layer of soil or sand. This happens constantly, so layers are always forming, and the oldest layers get pushed further and further down.

There are three major layers of soil in the lunettes at Lake Mungo. The oldest layer is the red Gol Gol soil at the bottom. Next is the grey Mungo layer, which was formed 25–45,000 years ago. The pale brown Zanci layer is on top and was formed 15–20,000 years ago.

By identifying the level at which the human remains were found, we can tell when they were buried and what was happening in that area at that period of time. In this case there was a great deal of animal and plant life at the level at which the bodies were buried. These clues include evidence of food and cooking, fireplaces and stone tools.

Evidence file 9

Climate analysis

Climate studies show that the area where the remains were found has undergone many climate changes that have affected the environment and habitat.

150,000 years ago the Willandra Lakes had formed in low-lying basins and were filled with water from the mountains to the east. Sand blowing off wave-formed beaches on the eastern shores of the lakes began to build lunettes.

A period of wetter climate and abundance arrived about 60,000 years ago. Rainfall in the Great Dividing Range sent the Lachlan River down the Willandra Creek channel to fill the lakes. For the next 20,000 years the lakes were full, the climate was stable and natural resources were plentiful. Archaeological evidence dates the appearance of the first humans in this area at around 40,000 years ago, although from an Aboriginal perspective people have always been in Australia since the land was created. 40,000 years ago the western dunes were vegetated and stable, and the lakes were surrounded by woodlands.

About 22,000 years ago, the climate entered a colder and drier glacial phase. Amid more fluctuations, the lakes began to gradually dry out. By 10,000 years ago the climate had become similar to today and remained relatively stable until the present. Vegetation continued to adapt to the conditions within the semi-arid climate. There was no permanent water, so people could not live there permanently. Europeans colonised in the Willandra area about 160 years ago, bringing sheep, cattle and other introduced animals in large numbers. The vegetation was changed and lunette erosion accelerated.

You can now complete your report.