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CrowdScience

What are these strange rocks?

Jul 10, 2026 · 26m

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CrowdScience listener Liana from Canada got in touch to ask about some very specific rocks she’d seen on an island in Indonesia – jagged, rugged and a very strange shape: hexagonal. They were in long columns, and clicked together like a jigsaw. But what are they, and how did they get there? Across the world in the UK, CrowdScience listener Sarah emailed us to ask about the famous rocks of the Giant’s Causeway in Northern Ireland. What makes them so uniformly hexagonal? Presenter Alex Lathbridge investigates, visiting the Giant’s Causeway to speak to geologist Dr Kirstin Lemon from the Geological Survey of Northern Ireland. She explains how this amazing landscape formed, and why the mythical…