United States Department of the Interior Geological Survey

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980

Depositional Environment of the Middle Proterozoic Spokane Formation-Empire Formation Transition Zone, West-Central Montana - 1980