Pilbara 2022

Chris Piper Science Teacher

Big Questions Expeditions took us on a trip through the Pilbara to places including North Pole Dome, Marble Bar, Karijini National Park, and Tom Price. The key stops on the trip covered the earliest life on Earth, banded iron formations, and mining iron ore. We were accompanied by several experts in the field of Geology: Professor Martin van Kranendonk (UNSW) who is an expert in the Pilbara region and in the field of early life, and Dr Mitch Schulte (NASA Mission Scientist from the Planetary Science Division (Mars Rover - Prosperity) who provided his expertise in the area of Geology and Planetary Geology. Both experts are board members of the Big Questions Institute, which previously had Professor Stephen Hawking as a board member! Other travellers on the trip were an artist, macadamia farmers, a parent, a journalist, and two venture capitalists. The purpose of the trip was to discover why Australia’s stromatolites are so important to the origin of life research and to the search for life on Mars and beyond.

The trip to the Pilbara was an experience that took us back to approximately 3500 million years ago, to a time when the oceans were green and the atmosphere was without oxygen. On this early Earth, there were bacteria living in shallow waters; the rocks and fossils of the Pilbara being part of the story behind these tiny organisms. Modern relatives of Earth’s early life can be found at Shark Bay in Western Australia and are called Stromatolites. These “living fossils” are photosynthetic, using sunlight to produce their energy. At the beginning of early life, when bacteria were less complex, they employed the process of chemosynthesis to obtain their energy. The bacteria grew as microbial mats in shallow ocean waters and secreted a sticky substance on their surface. Sediment in the oceans attached to this surface and the stromatolites grew. If sediment built up too quickly, the mats would be buried and the bacteria would die. However, the stromatolites grow quickly in some regions to stand proud above the sediment build-up.

Currently, the oldest fossils in the world come from the North Pole Dome and have been aged at 3.48 billion years old. They are amongst spinifex grass in an unremarkable gully within a large expanse. As Professor van Kranendonk relayed information about these fossils, we were drawn into a time and environment that was seemingly inconceivable. Once shown the evidence in the surrounding rocks (asymmetrical ripples), however, it was easy to understand the environment that the stromatolites were once living in, despite the remoteness and distance from the current coastline.

Moving onto the next site, we moved to younger stromatolites that were 3.3 billion years old. This site showed both differences and similarities in the geological processes that operated at the older North Pole Dome stromatolite site. The differences between the biological and geological layers became easier to recognise at this point. By the end of the day, we were able to see these structures everywhere and were very conscious of our foot placement when walking through these fragile and geologically important areas.

Dr Schulte’s interest in the Pilbara is related to his work with the Mars Perseverance mission that is addressing high-priority science goals for Mars exploration, including key questions about the potential for life on Mars. The mission takes the next step by not only seeking signs of habitable conditions on Mars in the ancient past, but also searching for signs of past microbial life itself. The Mars Perseverance rover introduces a drill that can collect core samples of the most promising rocks and soils and set them aside in a “cache” on the surface of Mars. Currently all samples taken on Mars remain on the planet, but planning is well underway for a Mars Sample Return Program when samples will be collected and returned to Earth by 2033. As stromatolites evolved, they started to produce oxygen and this, over time, caused the iron in the oceans to precipitate and fall to the bottom of the oceans. When this precipitation occurred the colour of the oceans changed to blue. Over many millions of years, layers of iron formed on the bottom of the oceans, some of which can be seen in the Karijini National Park. Over time the oxygen became more prevalent in the atmosphere as well.

The Karijini National Park has many gorges which can be viewed, walked, and swum through (despite the water being very cold). We ventured into the Joffre, Kalamina and Weano Gorges and saw the secondary products of those little bacteria–the banded iron formations showing layers of red and black rock; the black containing higher levels of iron. Not far from Karijini is Tom Price, a mining town whose primary role is the extraction of iron ore. The massive size and scale of the Rio Tinto operation has to be seen to be believed. The pit sizes, the machinery, the hours of operation, and the number of miners (FIFO and permanent) are all on a scale like nothing in suburban towns that most of us would know. What was amazing, was seeing the trains on the longest privately owned railway line in the world heading back to Tom Price to refill. We saw 15 trains, all with 238 carriages, each carriage capable of holding approximately 130 tonnes of material. There is something in the order of $25 million of iron ore on each train.

A big thanks to UNSW for sponsoring the cost of the trip, the School for supporting my attendance, and Professor Peter Wilson for providing the opportunity. Also, thanks to Darren and Kerryn for their fine work conceiving and developing the Big Questions Expedition to the Pilbara, which was such a fabulous opportunity to learn and educate in such an important area of Science.