Even more surprising, the delicate limestone spires were uncovered nearly 165 feet (50 meters) below the water’s surface. The discovery may mark the first time scientists have uncovered limestone pillars, called sea stacks, below the water’s surface. (Most of these sea stacks form on the coastline, above the water line.)
“Sea stacks are always eroding, as we saw with the one that collapsed in 2005, so it is hugely surprising that any could be preserved at that depth of water,” David Kennedy, a geographer at the University of Melbourne in Australia, said in a statement.
Kennedy was referring to one of the shoreline spires, which toppled spectacularly in 2005.
The limestone spires were formed through a process similar to the one that carved the famous tourist attraction of the Twelve Apostles, a handful of limestone stacks that jut out from the coastline of Victoria, Australia. These impressive sea stacks occur only when conditions are just right so that water and wind can erode a slab of rock into a steep, vertical column or columns: Rocks such as granite are too hard to erode quickly enough, while softer clay cliffs cannot support the weight of the overlying piles of rock. Limestone provides the perfect medium because it is soft but maintains a high compressive strength, the researchers wrote in the paper, which was published in the Journal of Coastal Research and will be presented today (March 10) at the International Coastal Symposium in Sydney.
Kennedy and his colleagues were surveying the seafloor to map the reefs around Victoria, which are home to abalone and rock lobster hunted by commercial fishermen. While mapping the ocean floor with sonar beams, Rhiannon Bezore, a doctoral candidate in geography at the University of Melbourne, found a series of short sea stacks next to some drowned cliffs.
Read more at Discovery News
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