Basaltic Ring Structure
A rimmed topographic depression within basaltic lava flow (Burr et al. 2009).
A type of hydrovolcanic feature.
Formation of the Columbia Plateau examples involved lava–water interaction, perhaps together with inflation (thickening) of the surrounding lava flows that produced basaltic dikes. Basalt extrusion occurred and the molten material was intersected by a rising groundwater table that rapidly accumulated volatiles. It caused venting, doming, and cracking. Fractures formed concentric to the focus of pressure release and were filled by melts. Subsequent catastrophic floods removed most of surficial material and left only the roots of the structure exposed on the surface (Hodges 1978).
KeywordsLava Flow Catastrophic Flood Topographic Depression Basaltic Lava Flow Basaltic Dike
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