Always grow. This meant that once the island’s surface was filled to the max, you first shot up into the sky; then when that effort reached the limit of the material strengths of the time, you had to dive. After the basements and subways and tunnels were aerated, no doubt people would start carving caves deeper and deeper, extending an invisible calvinocity down into the lithosphere, excavating earthscrapers to match the skyscrapers, buildings right down to the center of the Earth. Geothermal heating available at no extra charge! Apartments in hell: and that was Manhattan.
