**Abstract**

The Jos and Biu Plateaux volcanic provinces occupy the northeastern half of Nigeria bordering the Cameroon Volcanic Line, dotted with conspicuously visible number of dormant volcanoes with no reported activity. These dormant volcanoes represent potential future eruption sites. The ejecta materials of these volcanoes are essentially basaltic in composition and consist of sequence of pyroclastic materials, basalts, scoria and ash and are formed by strombolian and effusive styles of eruption. The volcanoes are represented by well-preserved cones and lava flows. In places the lava flows have been lateritized and eroded leaving remnants of weathered basalt boulders and a number of plugs and dome-like outcrops lacking any preserved cones. The basalts display essentially similar compositions consisting of phenocrysts of both olivine, plagioclase (bytownite–labradorite), with minor pyroxene (diopside-augite) embedded in a groundmass of plagioclase laths (labradorite), and accessory magnetite, ilmenite, k-feldspars, and volcanic glass. Geochemical data shows that these basalts are mainly alkaline olivine basalts derived from the deep mantle source enriched in incompatible elements similar to that of the Ocean Island basalts (OIB). Preliminary 40Ar-39Ar ages on the some of the basalts revealed Quaternary ages (Pleistocene epoch). The significant change in the composition of the Pidong Lake marked by decreasing pH is indicative of a probable input of juvenile fluids into the Lake. Also, the several incidences of volcanic eruptions along the close-by Cameroon volcanic line are pointers to the possibility for the reactivation of any of the dormant volcanoes in Nigeria. This work focuses on the need to assess the hazard level of some of these volcanoes for effective monitoring, disaster preparedness and land use planning as more people live and farm in these potentially endangered volcanic prone areas, unaware of the inherent risk.

**Keywords:** volcanoes, eruption, Jos Plateau, Biu Plateau, Nigeria
