scoria cone

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scoria cone (cinder cone, ash cone) Volcanic cone built of pyroclastic material (cinders and scoriaceous ejecta) usually of basaltic or andesitic composition, dominated by fragments 2–64mm diameter. These air-fall deposits build a straight-sided cone with slopes of about 30° (the angle of repose). Complex varieties may occur, including breached or gaping, and conewithin-cone types.