Giant's Causeway, Basalt, and Cornstarch
Cornstarch Aids Science's Uderstanding of Basalt Column Formation
Feb 23, 2009
Geology
The Giant’s Causeway is a geological formation found near Bushmills in Northern Ireland and off the Island of Staffa in Scotland. Designated a World Heritage site in 1986, the Giant’s Causeway is composed of distinct columns of five or six-sided basalt rock, formed from cooling lava, hardening from the outside edges inwards. If a great deal of water is present during this cooling process, it will seep into cracks in the cooling lava, turn into steam, and re-condense. This process, known as re-fluxing, causes the shape and distinctiveness of each basalt column.
Scientists have long known that the causeway was formed during the early Tertiary period about 50-65 million years ago. The epoch was one of intense igneous activity which produced a number of lava flows with pauses in between. This pattern cooled the outside of the flow, turning it to rock and leaving the interior still very hot. When the lava came into contact with water, (re-fluxing,) shapes that form the Giant’s Causeway, as well as other such formations in B.C. and California, were produced. The causeway is formed from approximately 40,000 columns, some as high as 25 metres.
Mystery Solved
Until recently, little was known about how the re-fluxing process functioned. The mystery has now been solved, thanks to the work of University of Toronto physicist Stephen Morris, Harvard mathematician L. Mahadevan, and doctoral student Lucas Goehring. Combining one part cornstarch and one part water, Prof. Morris and Lucas Goehring set the mixture to dry under a heat lamp for a week. A machine constantly weighed the cornstarch-water mixture and made adjustments to the heat lamp so that the drying rate was kept constant. The result of this procedure is a maze of tiny vertical columns identical to those found at the Giant’s Causeway.
Though this type of experiment has been replicated many times, the importance of the work done by Morris, Mahadevan, and Goehring was that they developed a quantifiable link between the time it took the cornstarch to dry and the size of the columns it produced. They found that the longer the cornstarch took to dry, the larger the columns it formed. Since the process for producing cornstarch towers is the same as that for building basalt towers, a correlation for time and development can be posited for the Giant’s Causeway and other such basaltic formations.
Legend
Though research has given science a clearer idea of how the Giant’s Causeway was formed, legend has played a role in how it received its name. The story says that Finn MacCool, the leader of a group of warriors who were the guardians of the king of Ireland, was ridiculed by a Scottish giant named Benandonner. The Scottish giant questioned Finn’s fighting prowess and, in retaliation, the Irish hero picked up a clump of earth and hurled it into Scotland as a challenge. Benandonner pitched a rock back at Finn shouting that if he got his hands on Finn, he would ensure that Finn’s fighting days were over, but as he could not swim, he would not be able to accomplish this deed. Finn, not willing to give up, tore large pieces from the cliffs and built the causeway for Benandonner to cross over. When the giant arrived, Finn played a trick on him, pretending to be a baby and biting the tip of his finger off. Benandonner felt that, if this were the baby, he did not want to meet Finn, himself, and ran back to Scotland, destroying the causeway as he went.
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