What Geological Event Caused the Distinctive Karst Towers of Halong Bay?

💡 The Answer

• During the Permian period, thick layers of limestone were deposited in a shallow tropical sea.
• Tectonic uplift in the Cenozoic era raised the limestone, exposing it to chemical weathering.
• Sea level changes during the last ice age flooded the valleys, leaving the resistant towers above water.
• The result is a 'fengcong' karst landscape with over 1,600 isolated limestone towers and islets.