Like all sinkholes, this cavity was formed by the collapse of a limestone floor situated above a cavity hollowed out by water flowing in a karstic relief. The diameter is around 50m, and the depth is around 15m, the area approximately 4,765 square metres (51,290 sq ft) and the perimeter 300m.[1] It is composed of blue clay and globigerina limestone that top the lower coralline limestone or żonqor.