Protecting the natural heritage in the Maltese islands (10)

Ħarq Ħammiem cave is situated on the north side of St George's Bay, St Julians. The entrance to the cave is at the base of an escarpment, located on the northern flank of the Ħarq Ħammiem valley. The cave constitutes a unique natural feature in the Maltese islands. It consists of two chambers on different levels, with an interconnecting narrow corridor leading from the upper chamber to a fully submerged lower chamber.

The cave is the only known fully submerged terrestrial cavern in the Maltese Islands. The water inside the cave approximates freshwater at the surface, turning brackish with depth and having seawater characteristics at deeper levels (below the floor of the upper chamber).

The cave was formed by a complex mechanism involving intense karstic activity and tectonics. There is ample evidence of both phenomena: (i) dissolution and concretional growth on the walls providing evidence of the karstic activity; and (ii) faults providing evidence of tectonism.

An example of the latter is the southern side of the upper chamber that constitutes a sheer vertical wall corresponding to a fault plane aligned along the longitudinal axis of the cave.

Mepa scheduled Ħarq Ħammiem cave, and the full extent of the remnant valley system, as an Area of Ecological Importance and Site of Scientific Importance as per Government Notice No. 370/08 in the Government Gazette dated April 23, 2008.