Archean felsic volcanic rocks lenticular fiamme. When hot pumice deposits on a cool surface, it is rapidly cooled, recrystallised and welded into quartz with flame-like ending tips. The eutaxiitc texture represents a hot vapour-phase emplacement of the fragmented volcanic materials on the Earth's surface. Flow bands are present in massive, uniform felsic lava flow units. When the viscous lava flow encounters a surface, friction drags the mobile lava and forms internal banding. Structureless hyaloclastite is commonly found in Archean felsic volcanic rocks. In submarine environments, water quenches and cools lava rapidly during volcanic eruption. The flow is fragmented and form glassy volcanic breccia. The
Geology of Ascension Island same time as the Sister's Peak region 829,000 years ago. Bentmoreite scoria cones record evidence of mafic volcanism, although older rhyolite and trachye flows, domes and pyroclastic deposits point to felsic eruptions as well. The Central Felsic Complex (CFC), centers on Green Mountain and Middleton Ridge and is older than the Eastern Felsic Complex. Here, ash is typically welded together and breccia is laden with rhyolite and obsidian fragments. Middleton Ridge formed more than one million years ago and is accompanied trachyte and rhyolite flows. By comparison, Green Mountain formed as recently as 395,000 years ago with trachyte flows and