Il-Wied ta' San Martin and Il-Ballut are two important valley systems that are inextricably linked to the geomorphology of Il-Wardija ridge. These two valleys receive a continuous supply of water from two permanent springs: Għajn Astas and Għajn Ballut.

San Martin Valley

The watercourse of Il-Wied ta' San Martin hosts a population of the endemic Maltese freshwater crab (Potamon fluviatile lanfrancoi). This crab is associated with the presence of running water all year round, a feature that is quite rare in the Maltese islands. Consequently, this species has a very restricted distribution at a national level. Il-Wied ta' San Martin is also associated with records of the freshwater mussel (Pisidium casertanum).

Il-Ballut

The headwaters of the valley at Il-Ballut support a Holm Oak (Quercus ilex) forest remnant. The forest remnant at Il-Ballut is very important since it constitutes the oldest known population of Holm Oak in Malta, and is also associated with high species diversity. Some of the trees are estimated to be about 500-900 years old.

This forest remnant also supports species that are closely associated with the Holm Oak and are consequently rare in the Maltese islands.

The site is particularly rich in mycoflora (fungi), most of which are exclusive to the forest remnant.

There are also four species of lichens, nine species of myxomycetes (slime moulds) and three species of insects that are exclusive to the area. Il-Ballut is also the only known locality for the Serotine bat (Eptesicus serotinus).

Mepa scheduled San Martin valley, the remnant Holm Oak forest at Il-Ballut, and their equally important context, as per Government Notice No. 1137/08 in the Government Gazette dated December 19, 2008.