Dike
Dikes are tabular or sheet-like bodies of lava that cut through and across the layering of adjacent rocks. They form when magma rises into an existing fracture, or creates a new crack by forcing its way through existing rock, and then solidifies. Hundreds of dikes can invade the cone and inner core of a volcano, sometimes preferentially along zones of structural weakness.
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Dikes in Valle del Bove, Etna. Note solitary dike in the background. Photo: J. Alean |