The lavas of Uvea Island, in the Wallis group, include olivine basalts containing colorless monoclinic pyroxene, less abundant olivine basalts containing titaniferous pyroxene, and oligoclase andesite. Palagonite tuff builds cones along the eastern coast. Of the lesser islands in the Wallis group, Nukuatea is built largely of palagonite tuff, with a flow of olivine basalt; Nukufetau is composed of olivine basalt flows and cinders; Luaniva is composed largely of olivine basalt with a little tuff; and Fugalei of olivine basalt which filled the bowl of a tuff cone, most of which has been eroded away. Other islets represent the emergent edge of the barrier reef and are composed of poorly to well-consolidated calcareous sand. The lavas of the Wallis Islands belong to the alkaline suite of the central Pacific volcanoes, rather than to the calc-alkaline suite of the circum-Pacific belt.

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