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SYDNEY, March 10 (Reuters) - Massive underwater limestone towers have been found in line with Australia's famous '12 Apostles' ocean rock formations, in a surprise discovery that scientists said was previously thought impossible.
The five underwater columns, dubbed by scientists the 'Drowned Apostles', are around 10 metres (32 feet) tall and continue the chain of the '12 Apostles', which are up to 40 metres (130 feet) tall off the coast of the southern state of Victoria and a major tourist attraction.
It is believed the underwater towers were submerged and preserved by rapidly rising sea levels at the end of the last Ice Age around 11,000 years ago.
"This is the first time in the world we have seen underwater sea stacks. They don't last long due to erosion and according to all the textbooks they shouldn't be there," said Melbourne University geologist David Kennedy.
Sea levels are believed to have risen during peak melting points at the end of the last Ice Age, fast enough to preserve the shape of the unique rock formations which are believed to date back around 60,000 years, said Kennedy.
"They most likely used to be taller but were shaved down by the rising sea. The sea rise was so rapid the waves just went over the top and they didn't have time to knock them over," said Kennedy.
The 'Drowned Apostles' discovery was published in the Journal of Costal Research by postgraduate student Rhiannon Bezore, who along with Kennedy, stumbled upon the find when analyzing previously unstudied sonar mapping of the area.
A major draw-card for tourists along Victoria's Great Ocean Road, the '12 Apostles' have had their numbers reduced over the years due to rapid erosion. The most recent collapse in 2009 left only seven remaining columns.