**2.1 Geology of the Pidong maar**

The Pidong volcano is hosted by medium to coarse grained granite gneiss rocks of PreCambrian age [11]. The volcano extrudes through three craters arranged in a N-S direction with the southernmost breached by water. The Pidong maar is bounded to the south and southeast by granite gneiss rocks and to the west, north and northeast by pyroclastic surge deposits explosively ejected during formation (**Figure 1**). The volcanic ejecta consists mainly of pyroclastic materials, scoria, basaltic lava, pulverized granite materials, and volcanic ash [3, 9, 12]. Beside the lake's crater rim to the extreme south-east are characterized by deposits of large boulders of granite rocks and this is evident of the high explosion that characterized the eruption of the Pidong Maar/Lake [9].

*Hydrogeochemistry of the Pidong Crater Lake, Jos Plateau Volcanic Province, Nigeria… DOI: http://dx.doi.org/10.5772/intechopen.99720*
