One of the largest volcanic fields in the western United States, the Marysvale straddles the Colorado Plateau-Great Basin transition zone.

Most igneous rocks belong to a middle Cenozoic (~32 to 22 million years old) calc-alkaline sequence, although about 5% are related to an upper Cenozoic (23 million years to Holocene) bimodal (basalt and rhyolite) sequence.

The Marysvale contains a variety of volcanic features, including stratovolcanoes, calderas, lava domes, and cinder cones.

The field is an example of intraplate volcanism; its earlier deposits are thought to be related to Farallon plate subduction, while the later bimodal assemblage (especially the basalts) have been linked to Basin and Range extension.

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