Intrusive Landforms

Intrusive Landforms Intrusive landforms are formed from bodies of magma cooling below the Earth’s surface They form rocks with coarse texture and visible minerals (granite, gabbro, diorite) rather than the fine textured rocks formed by volcanic landforms (basalt, pumice, scoria)

Shallow Intrusive Structures Volcanic neck – extinct throat of a volcano Dike – tabular igneous bodies that cut across other layers and are nearly vertical or at steep angles Black Tusk in Garabaldi Prov Park Near Squamish and visible from Hwy 99

Shallow Intrusive Structures Sill – nearly horizontal tabular igneous bodies Laccoliths – start out as sills, but become wider as they fill with more magma (bulged sills)

Deep Intrusive Structures Batholith – a large area (>100 km2) igneous intrusion Stocks – smaller area igneous intrusions (< 100 km2)

Deep Intrusive Structures Xenoliths = large chunks of older rock that is included in an igneous rock body Pluton = A body of intrusive igneous rock that is crystallized from magma slowly cooling below the earth’s surface.