It is an oval-shaped layered intrusion that was formed during five phases of magmatic activity.

Geologists can now identify characteristic patterns in seismic waves that indicate particular magmatic activity.

This increased in magmatic activity corresponds to increased mantle activity and the Earth's magnetic field.

It formed during a period of magmatic activity associated with the large Midcontinent Rift system about 1,100 million years ago.

All tectonic and magmatic activity ended by the time the Cambrian sandstones were deposited, about 530 million years ago.

Ages are approximated from the magmatic activity associated with the individual cycles of the orogeny.

Many rifts are the sites of at least minor magmatic activity, particularly in the early stages of rifting.

At least five hot springs exist in valleys near Mount Cayley, providing more evidence for magmatic activity.

During this period, four episodes of magmatic eruptive activity have been recently recognized.

This is the last episode of undoubted magmatic activity preserved in the geologic record.