A batholith is a large mass of intrusive igneous rock, larger than 100 km2 (40 sq mi) in area, that forms from cooled magma deep in Earth's crust. Batholiths are almost always made mostly of felsic or intermediate rock types, such as granite, quartz monzonite, or diorite.
Half Dome, a quartz monzonite monolith in Yosemite National Park and part of the Sierra Nevada Batholith
The eroded laccolith above the batholith system of Vitosha - Plana domed mountains, next to Sofia, Bulgaria
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.
Devils Tower, United States, an igneous intrusion exposed when the surrounding softer rock eroded away
An intrusion (pink Notch Peak monzonite) inter-fingers (partly as a dike) with highly metamorphosed black-and-white-striped host rock (Cambrian carbonate rocks) near Notch Peak, House Range, Utah, United States
Dark dikes intruded into the country rock, Baranof Island, Alaska, United States