@salt_shack_geology: Learn your localities - Benagil Cave 🇵🇹 Benagil Cave looks like someone simply punched an enormous hole through the roof of a limestone cliff. The reality is considerably more interesting. Its shape is the result of multiple geological processes working together over millions of years: carbonate sediments forming in a shallow Miocene sea, limestone becoming fractured and karstified by mildly acidic water, Atlantic waves exploiting those weaknesses, and gravity eventually helping sections of the cave roof collapse. So the famous “eye” in the ceiling isn’t just a photogenic accident. It’s the visible result of chemistry, erosion, rock structure and time all conspiring to dismantle the same bit of coastline. And having finally visited it ourselves, I can confirm it is every bit as spectacular as it looks. #BenagilCave #Geology #Karst #Portugal #LearnYourLocalities

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Friday 11 September 2026 13:04:10 GMT