Why Are Aran Islands Made of Pure Limestone?
🕐 7 min read | 🌍 Natural Wonders 🔒 Key Takeaways The three Aran Islands—Inishmore, Inisheer, and Inishmaan—consist almost entirely of Carboniferous limestone formed 320 million years ago from compressed marine organisms on a tropical seafloor. Western cliffs of Inishmore tower 270 meters (886 feet) above the Atlantic, among Europe's tallest limestone coastal formations, reshaped by Atlantic wave energy exceeding 3,000 kilowatts per square meter during winter storms. The islands' soluble limestone creates karst terrain with dozens of caves, underground streams, and sinkholes where rainwater dissolves bedrock at 1-2 millimeters per century. Specialized Arctic-Alpine plant species including the rare Aran orchid (Spiranthes romanzoffiana), spring gentians, and mountain avens thrive on bare limestone pavement at sea level—nowhere else found at such low elevation in Ireland. Towering 270 meters above the Atlantic, the Aran Islands rise as raw limestone monuments for...