The scientists on the team conjectured there used to be a lost limestone plateau, or a hypothetical “Henoko karst tableland,” on and around Nagashima. They also inferred a vast karst area ...

This unfinished subterranean chamber, an unfinished chamber within Khufu's Pyramid, lies 90 feet (30 meters) below the surface of the plateau ... chipped away at the limestone bedrock to build ...

Later on, plate action saw mountain building and continents colliding, with the former ocean floor uplifted out of the sea to form the broad plateau which is the limestone landscape of Ireland.