What are these strange rocks?

What are these strange rocks?

July 10, 2026 · 26 min

About this episode

The episode explores the origins and characteristics of hexagonal rocks, including those at the Giant's Causeway and in Indonesia.

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 rocks look the way they do today. We also hear from Dr Alfend Rudyawan from Institut Teknologi Bandung in Indonesia about Liana’s intriguing rocks. Are these distant locations more closely related than you might think? And we look to nature – because angular, uniform hexagons crop up surprisingly often. Professor Jean-Marc Schlenker from the University of Luxembourg explains why hexagons are much better than other shapes. Presenter: Alex Lathbridge Producer: Hannah Fisher Editor: Ben Motley…

People in this episode

Host: Alex Lathbridge

Guests: Dr Kirstin Lemon, Dr Alfend Rudyawan

Topics covered

Mentioned in this episode

Organizations: Institut Teknologi Bandung, Geological Survey of Northern Ireland, University of Luxembourg

Places: Canada, Indonesia, Giant’s Causeway, Northern Ireland

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