Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form intrusions, such as batholiths, dikes, sills, laccoliths, and volcanic necks.
On March 22, 2014, a large landslide near Oso dammed the North Fork of the Stillaguamish River, with mud and debris covering an area of one square mile (2.6 km2).
Intrusive rocks are characterized by large crystal sizes, and as the individual crystals are visible, the rock is called phaneritic.
An intrusion is any body of intrusive igneous rock, formed from magma that cools and solidifies within the crust of the planet.
An intrusion is any body of intrusive igneous rock, formed from magma that cools and solidifies within the crust of the planet.