Figure of western U.S showing
the track of the Yellowstone hotspot as assumed by younging in a northeast
direction of silicic calderas (yellow). Areas colored in shades of tan
represent Neogene sedimentary deposits contemporaneous with the hotspot
volcanism. Black dots are sampling locations of Yellowstone/Snake River
Plain volcanic ash deposits. All radiometric ages for units in the interval
including 4.49 Ma to 10.27 Ma are ages determined by Ar/Ar analysis at
the Lamont-Doherty Earth Observatory Geochronology Laboratory and the at
the Berkeley Geochronology Center. Many age determinations are based
on weighted averages of as many as 16 individual age determinations.
Click for detail of calderas.