GeoLog

Imaggeo on Mondays: Finger Rock

Finger

Standing proud amongst the calm waters of Golovnina Bay is ‘The Devil’s Finger’, a sea stack composed of volcanic sediments. Located on the Pacific coast of Kunashir Island -which is controlled by Russia but claimed by Japan – the stack is testament to the volcanic nature of the region. The island itself is formed of four active volcanoes which are joined together by low-lying geothermally active regions.

Sea stacks, tall columns of rocks which jut out of the sea close to the shore, are common across the world, with famous examples found in the UK, Australia, Thailand, Ireland and elsewhere. Sea stacks are formed naturally by erosion processes. Headlands which protrude out towards the sea are subject to many years of battering by wild winds and seas. Slowly, the force of the wind and sea weakens, cracks and breaks up the rock and a cave is formed. The process continues, particularly during stormy weather spells, when eventually an arch is formed. Given more time, the arch too breaks away, leaving a solitary tower of rock, such as that seen in this week’s Imaggeo on Mondays picture. In case you are looking to expand your Russian vocabulary, it might be useful to know that Russian term for sea stack is ‘kekur’!

Laura Roberts-Artal
Laura Roberts Artal is the Marketing Manager at PDS Ava (part of PDS Group) and Associate Director of Communications for Geology for Global Development. Laura was the Communications Officer at the European Geosciences Union from the summer of 2014 to the end of 2017. Laura is a geologist by training and holds a PhD in palaeomagnetism from the University of Liverpool. She tweets at @LauRob85.

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