|A Dike of Cenozoic Age Cutting Folded Layers |
(Richard Warner, British Geological Survey and Donald Fay, Open University Geological Society, UK.)
A dike of Cenozoic age cutting discordantly across complexly folded wackes
Augrim quarry, Co. Down, Northern Ireland.
The dike is the 2 - m - wide reddish feature, passing nearly vertically up the rock face behind the person in the foreground.
A dike is a large slab of rock that
cuts through another type of rock. Dikes are tabular or sheet-like bodies of magma 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.