Volcanism of the mafic capping stage began with the eruption of aphyric hawaiite lava flows. These were extruded from dikes and dissected cinder cones in the central and southeastern parts of the Itcha Range. Alkali olivine basalts were erupted contemporaneously from younger better preserved cinder cones and form lava flows reaching thick. Once the alkali olivine basalt flows cooled, they formed well-developed columnar joints. Feldspar-phyric, highly vesiculated hawaiites and benmoreites were later erupted from several vents on the summit of Itcha Mountain.