POWERHOUSE COLLECTION

Pumice collected from Mt Erebus during Shackleton's British Antarctic Expedition, 1907-9

Object No. C4737

This pumice was collected in March 1908 on Shackleton's British Antarctic Expedition (BAE) by the first explorers to climb Antarctica's Mt Erebus, including Australian geologists Edgeworth David and Douglas Mawson. Erebus, an active volcano, was covered in snow and belching steam and sulphur dioxide. At its peak the scientists measured the boiling point of water, which falls as altitude increases. They calculated the height of Erebus from that temperature, and from the air pressure indicated by their barometer. The average was 13,370 feet (4075m, compared to the now accepted height, 3794m). Debbie Rudder The BAE, otherwise known as the Nimrod Expedition after the name of the ship on which the explorers sailed to Antarctica, was led by Sir Ernest Shackleton. The expedition's main aim was to be the first to the South Pole but this goal was not reached. However, the expedition did achieve the record for the furthest point south reached to that date, 88 degrees 23 minutes South. The 1907-1909 BAE is also renowned for its geological and scientific achievements as well as its members becoming the first to reach the South Magnetic Pole and the summit of Mount Erebus. It is significant that pumice was found on top of Mount Erebus as it can act as a geological "time mark". Pumice-bearing geological strata reveals the age of a volcano as well as the frequency and magnitude of its eruptions. The average size of pumice pieces at a volcanic site and their prevalence can also tell the story of a volcano's history, internal functioning and changes over time. Pumice is a type of igneous rock formed as a result of the solidification of foam produced by the escape of gases in molten magma. This occurs on or near the surface of the earth under little more than atmospheric pressure. The stone is vesicular as a result, meaning that it is full of small, round, gas filled cavities, with a specific gravity so low that dry pumice actually floats on water. Interestingly the word pumice is a derivative of the Latin word 'pumex' meaning foam. Although saturated pumice can be found scattered over a considerable amount of the world's ocean floor, apart from large deposits on the Italian island of Lipari and Japanese island of Nii-jima where it is commercially mined, there are few known extensive deposits on land. Rebecca Anderson, Volunteer under the supervision of Margaret Simpson, Curator, Science & Industry, March 2013. References Fenton, Carroll Land and Mildred Adams Fenton, The Rock Book, (Mineola, N.Y.: Courier Dover Publications, 2003) pp. 122 - 129. Hoowe, J. Allen, Common Commodities and Industries: Stones and Quarries, (London: Sir Isac Pitman and Sons, Ltd., 1937) pp. 15-18. Larson, Edward J., An Empire of Ice: Scott, Shackleton, and the Heroic Age of Antarctic Science, (USA: Yale University Press, 2011), pp. 126-282. Mills, William J., Exploring Polar Frontiers: A Historical Encyclopaedia, Volume 1, (California) ABC-CLIO, 2003) pp. 3-4. Royal Society for the Encouragement of Arts, Manufactures and Commerce, "Italian Pumice Industry", Royal Society of Arts, Vol. 69, No. 3583 (July 22, 1921): pp. 591-592. Sterba, Johannes H., Michaela Foster, Max Bichler, Charalampos Vasilatos and Michael G. Stamatakis, "Analytical identification of a single source pumice from Greek shores and ancient sites in the Levant", Hellenic Journal of Geosciences, Vol. 45, (2010) pp. 293-298.