The Mġarr ix-Xini area lies along the southern coast of Gozo and is affected by one of the largest fault complex systems of the island. There are two main faults in the area, including one which strikes WNW towards Sannat and another which strikes NE from Mġarr ix-Xini to Għajnsielem and Qala. The deep valley and the inlet of Mġarr ix-Xini are the surface expression of the tectonic depression at which these faults originate.
Wied ta’ Mġarr ix-Xini is a steep-sided valley which developed along the zones of weakness formed by the fault lines. This valley bisects the landscape from north-west to south-east, incising an impressive deep meandering gorge into the lower coralline limestone that flows directly into the sea forming the inlet of Mġarr ix-Xini. The only other valley in Gozo which flows directly into the sea is Wied ix-Xlendi. The cliff faces are very rich in karstic features including a large number of depressions and caves.
MEPA scheduled Wied ta’ Mġarr ix-Xini and the contiguous coastal cliffs as a Level 1 Site of Scientific Importance and a Level 1 Area of Ecological Importance as per Government Notice No. 937/01 in the Government Gazette dated 9 November 2001.