Southwestern Region
333 Broadway SE [map]
Albuquerque, NM 87102
(505) 842-3292
TTY: (505) 842-3198

GILA

The Gila National Forest lies mainly within the Mogollon Plateau of the Mogollon-Datil volcanic field.  Volcanism in the Mogollon Plateau began approximately 40 million years ago.  Volanic units in the Mogollon-Datil volcanic field include domes, lava flows, intrusions, and numerous ash-flow tuffs or ignimbrites.  Many of the ash-flow tuffs erupted from large resurgent calderas, similar to the Valles Caldera.  Within the Mogollon-Datil volcanic field, there are as many as 11 latest Eocene and Oligocene silicic calderas and their associated sheets of  ash-flow tuff. 

The character of the volcanism in the Mogollon-Datil volcanic field changed with time.  From 40 to 36 million years ago, basaltic andesite to andesite volcanoes were active.  From 36 to 24 million years ago, the volcanism was bimodal, consisting of both basaltic andesite and silicic volcanism. This phase of volcanism is sometimes known as the "ignimbrite flareup".  The last phase of magmatism was predominantly basaltic, related to Basin and Range tectonism. 

Since the volcanism occurred, the Mogollon-Datil volcanic field has been undergoing Basin and Range extension and faulting, so today an ash sheet that was originally continuous might be discontinuously exposed in fault-block mountains separated by down-dropped basins.

The volcanism in the Mogollon-Datil volcanic field is thought to be related to low-angle subduction of the Farallon plate or to extension of the crust following the thickening of the Laramide orogeny (the mountain-building event that created the Rocky Mountains).

Click on the district names on the map above or on the links below to view information on a specific area.

• Black Range
• Glenwood
• Quemado
• Reserve
• Silver City
• Wilderness