The coastal plain of Gaza is composed of sand dunes and fertile sandy sediments. Except for a porous calcareous sandstone called kurkar in Arabic, there are no other rocks in this region. In contrast, the West Bank is dominated by low mountains: Mount Gerizim (881m), Nabi Samwil (890m), and Mount Scopus (826m). The rocks are principally composed of marine sediments (limestone and dolomite). The porosity of these rocks permits water to filter down to the non-porous strata, which supply water to the numerous aquifers in the region.