Interpretive reconstruction of the Yellowstone Plateau region before initial plateau volcanism

Interpretive reconstruction of the Yellowstone Plateau region before initial plateau volcanism (a little before 2 million years ago). The region was entirely an elevated and faulted mountainous terrain with no basin in the present plateau area. Gray areas are underlain by ash flow deposits from calderas of the eastern Snake River Plain area that predate the Yellowstone volcanic system.  Figure 6 from Christiansen (2001) (https://pubs.usgs.gov/pp/pp729g/).