The corresponding chronostratigraphic unit is the Yavapai Series, which locally defines an interval of geologic time.

Exposures are found from the Jerome — Prescott area southwest to Mingus Mountain and in other parts of the Arizona transition zone.

They were subsequently formally named as the Yavapai Schist by Thomas Jaggar and Charles Palache in 1905.

Wilson investigated theunit again in 1939, raising it to group rank, dividing it into the Yaeger greenstone, Red Rock Rhyolite, and Alder sedimentary series.

Wilson also recognized that the beds had been seriously deformed during the early Proterozoic and named this episode the Mazatzal orogeny.