“We entered a total rock rubble slick made up of pumice stones from marble to basketball size,” the couple said on their Facebook page. “The waves were knocked back to almost calm and the boat was slowed to one knot. The rubble slick went as far as we could see in the moonlight and with our spotlight.” Mick Hoult with a sample of the pumice he encountered sailing to Fiji. Credit:SailSurfROAM Pumice is formed when lava is ejected from a volcano into water and cools into a light, bubble-filled rock that floats. In this case it came from a large underwater eruption on August 7 from a relatively new unnamed volcano, and the Australian sailors collected samples they would take to QUT geologist Scott Bryan.

Associate Professor Bryan has been studying the unusual rock raft phenomena for some time and said it was more common than most people thought. “We see it happen every five years or so. There was a big event in 2013 where a lot of pumice washed up on Australian beaches, that was from the Havre volcano,” he said. The path of the pumice through the region following the eruption. Credit:QUT “This is a fairly regular occurrence in that region, so since the Havre eruption we were a little overdue.” The pumice raft will be carried by ocean currents and travel through the South Pacific region, eventually washing up on Australian shores by early next year.

Pumice washed up on beaches in Queensland in 2013 following the 2012 eruption of the Havre Seamount volcano, the largest of its kind in 50 years. Credit:QUT As it travels it will pick up all sorts of small sea life, from small animals to algae and coral. Professor Bryan said the timing was almost perfect as it would be travelling past New Caledonia around November, right when coral in the region was spawning. “This is the mechanism which allows corals from one reef to attach to the pumice and be carried thousands of kilometres to arrive at a new location,” he said. “In this case that would be the Great Barrier Reef, which will see an influx of new coral from this process.”