Welcome to my website. My name is Penny Sackett and I am the Chief Scientist for Australia. What does this mean exactly? Keep reading to find out…

• 15 October 2009

Welcome to my website. My name is Penny Sackett and I am the Chief Scientist for Australia. What does this mean exactly? Well, as Chief Scientist I:

• provide independent, evidence-based advice on science and innovation to the Prime Minister and other Ministers to inform Government policy across all portfolios and time frames;
• am an advocate for science to government, industry and the public;
• am an ambassador for Australian science internationally;
• play a key role in relevant governance bodies pertaining to science;
• foster collaborative relationships among scientific and research institutions, industry and governments, with the aim of improving the economic and social impact of science in Australia; and
• promote scientific understanding, skills, careers, and informed scientific discussion throughout society.

What do you think of when you hear the word science? To me, science is a creative endeavour that allows us to ask questions of the world around us and build the tools to translate the answers that the world whispers back.

Science can explain many of the phenomena we see around us every day. I recently went on a holiday to the Kimberley region in WA, a truly beautiful part of Australia. The scenery was spectacular – even more so when one considers what the landscape is whispering to us in the language of science.

The Bungle Bungles

The Bungle Bungles are a range of orange and black striped beehive-like hills that rise 300 metres above the surrounding plain in Purnululu National Park in the Kimberley. They are made of sandstone, one of the most common rock types in the world, but they look like nothing else on earth.

Geology tells us that the rock that makes up the Bungle Bungles has a long history. About 1.7 billion years ago, when the earth was only about one-third its current age, vast moving pieces of the earth’s crust collided with one another to push up an ancient mountain range. Over a period of time 350 to 500 millions ago, this ancient range eroded, and its sands and silts were deposited over the flat low-lying flood basins to the east. Over time, the debris was laid down in layers and consolidated into sandstone to form the layered rock that would become eventually become the younger Bungle Bungle mountain range.

About 70 million years ago, the whole region was uplifted, pushing the sandstone up as a single block. Tropical weathering removed much of the silica “cement” that binds material in hard rock. This meant that all layers, soft ones and previously hard ones, would now be equally susceptible to any future harsh weathering. That happened about 50 million years later when the region was again thrust up by the moving crust of the earth, cracking the Bungle Bungles to create joints where erosion and weathering occurs more quickly. All weakened layers of sandstone weathered uniformly along these joints to create the unusual smooth clusters of beehive-like formations.

Perhaps one of the other reasons one is reminded of beehives when looking at the Bungle Bungles is their orange and black “bee-like” stripes. What causes the colours? Geochemistry and biology give us the answers here. Without its silica glue, the sandstone is more porous, so rain can soak further into its surface, carrying with it iron oxide (Fe₂O₃ = rust!), giving the surface an orange colour. The dark grey bands are areas of more porous sandstone that has provided the right amount of moisture for lichen and algae to grow. (The same sort of algae that are responsible for much of the oxygen we breathe in the atmosphere, but that’s another story for another day).

The result in the Punululu? Sheer beauty and a wonderful place to spend some time with nature. But don’t clamber up the Bungle Bungles; they are fragile without their silica cement.

Wolfe Creek Crater

Approximately 300,000 years ago, a short time ago on geological time scales, a meteoroid (basically another old rock, but this one from outer space) weighing about 50,000 tonnes and travelling at something like 50,000 km per hour crashed into the Great Sandy Desert.

What remains now is a circular impact crater about 875 metres in diameter with a flat floor that — after some filling in by drifting sand — is now about 60 metres below the crater rim.  Wolfe Creek Crater was only discovered by people of European descent in 1947 during an aerial survey, but Aboriginal people have long known about the crater, which they call Kandimalal.  Aboriginal Dreaming tells of two rainbow snakes who formed the nearby Sturt and Wolfe Creeks as they crossed the desert.  The crater is believed to be the place where one snake emerged from the ground.  The Wolfe Creek National Park now protects the crater and its immediate surrounds, but if you are up for long, bumpy ride to the Park along the Tanami highway, you can visit this special place.

So will another meteoroid or even a larger asteroid hit the earth and what will happen if it does?  Most meteoroids burn up in our atmosphere before reaching the earth’s surface, but some do survive the trip.  For example, it is widely accepted that an object 30 to 50 metres wide exploded over Tunguska in Siberia in 1908, flattening trees for dozens of kilometres all around. The chance of a similar impact is about 1 in 500 years (Nature, vol 453, p 1178).

As the diameter of an object increases, so does its impact if it collides with earth – one less than 100m across would cause an impact similar to that felt by Siberia in 1908, while one several hundred metres wide could cause massive tsunamis if it crashed into an ocean. The crash of an asteroid larger than 1 km in diameter has the potential to perturb the global climate in a way similar to a ‘nuclear winter’.  However, the chance that such large objects will strike the earth is much, much smaller than for relatively small ones like the Tunguska.

For up to date news on meteorites please visit New Scientist and ABC Science.

I’ll be checking in from time to time on this blog, and I hope you will too.