Adapted from ©iStockphoto/SVLumagraphica
If anyone thinks that rocks need millions of years to form, then experiments carried out by Murdoch University (Perth, Western Australia) researchers would surely overturn that idea.
That’s because the researchers have been able, with the help of added microbes, to turn sand into stone rapidly.1
Starting with soft sand, and applying the bacterial treatment, “we found that it turns harder each time”, said Dr Ralf Cord-Ruwisch. “At the very end, it turned into something resembling marble more than sandstone.”
From soft sand to marble-hard rock, quickly!
“The biggest block we have made so far was in a shipping container,” said Dr Cord-Ruwisch, “just to prove that it can not only work in the laboratory.”1
The results of the research have excited many people who can see that such ‘biocement technology’ will be a great boon to construction and mining industries—not just to people wanting “to take their sandcastle home from the beach in the form of a solid rock sculpture”.
A Dutch company sent sand samples from Holland for testing. Dr Cord-Ruwisch explained that the Netherlands has a keen interest in solidifying the dikes that prevent the sea from flooding that country’s vast areas of reclaimed low-lying land.
“Dikes would normally be made of rocks, solid stuff, but Holland is a bit like Perth in that they only have sand,” he said. “While dikes made from sand are long lasting, there are certain risks if water intrudes into the dike sand and lubricates the sand particles so they start shifting against each other. Then you can have some instability of the dikes.”1 The Dutch have been impressed by the capability of the bacteria to cement the sand samples—hard.4
A major practical application for the biocementation technique will be in mining. “It doesn’t need oxygenation,” Cord-Ruwisch explained. “In theory we could solidify the sea bed before drilling for oil. We could also drill tunnels in the sand, we could make the sand harder so it doesn’t cave in.”1
The take-home message from all this? In the global Flood of Noah’s day (about 4,500 years ago), there would have been lots of microbes ‘floating around’ and buried in sand in low-oxygen conditions, just right for them to release cementing agents into the surrounding sediment. Little wonder then we see as a legacy of that watery event, lots of beautifully preserved creatures (fossils) in layers upon layers of rock-hard sediment!
References and notes
- Calvo, S., Scientists turn sand to stone, Science Alert, www.sciencealert.com.au/content/view/19095, 7 May 2009. Return to text.
- Formerly known as Bacillus pasteurii. Return to text.
- When in a calcium-rich environment, the bacterium’s urease enzyme (which hydrolyses urea) generates binding calcite cement (calcium carbonate) as a by-product. Whiffin, V., Microbial CaCO3 precipitation for the production of biocement, PhD thesis, 2004—Abstract viewed via Murdoch University Digital Theses Program, https://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20041101.142604, last accessed 22 October 2009. Return to text.
- Murdoch University Synergy 6(2): Winter 2002, Biocement for sandcastles, about.murdoch.edu.au/synergy/0602/biocement.html, last accessed 22 October 2009. Return to text.