[2] Neither the base nor the top of the formation are exposed, but it is separated from the slightly younger Big Bug Group by the Shylock fault to the west.

[2] The Ash Creek Group hosts numerous ore deposits, including the Jerome copper mine.

[4] Between 1883 and 1952, these produced 736,000 tons of copper and valuable amounts of gold, silver, lead, and zinc.

The ore bodies were emplaced in a hydrothermal system very shortly after deposition of the Cleopatra Rhyolite, about 1738.5 million years ago.

[2] The beds belonging to the unit were first named as the Ash Creek Group by C.A.