Approximately three to 10 miles below these volcanoes are the magma chambers that feed them, which build up over time as bodies called plutons. This rock, once it cools, will become the type of granite that is exposed in Yosemite. Plutons are large (often covering over 400 square miles) and are typically formed by many pulses of magma over a few million years. The granite that composes an individual pluton will have a relatively homogeneous texture and composition, displaying minor variations across its extent. There are roughly 35 individually defined plutons in the Yosemite area. Plutons are usually named after a famous landmark that is dominantly made of that rock (examples include the Half Dome Granodiorite and the El Capitan Granite).