A unique type of valley which can be found in various localities of the Maltese Islands has been documented by an international team of scientists from the University of Malta..

The scientists explained that this valley, which has a theatre-shaped head, wide and flat bed, and vertical side slopes, is formed by groundwater seepage rather erosion by surface water, which is the case for most valleys worldwide.

There are thirty valleys formed by groundwater on Malta and Gozo, with the most prominent examples located in Mgarr (including Gnejna Valley), Mellieha and Nadur.

There are an additional twenty three such valleys on the seafloor, mostly located offshore of the north-eastern coast of Malta and Gozo – Marsalforn.

It was explained that there are a number of important implications associated with this discovery. First, this is the first time that groundwater seepage has been demonstrated to form valleys in rock. These valleys therefore deserve additional protection in view of their uniqueness.

Secondly, these valleys can be used to reconstruct environmental and water conditions in the past, which is very useful in places where the geological record is poor, such as in desert environments or potentially even Mars, where similar valleys have been documented.

Thirdly, the scientists show that the valleys are retreating at a rate of about 2cm per year in the form of block landslides.

They said that this is an important consideration when assessing the hazard associated to these valleys, especially for owners of fields located above or within the valleys.

The study, which is a product of the MARCAN project and was led by Prof. Aaron Micallef from the Department of Geosciences, has now been published in the international journal Geology.

Photo: University of Malta

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