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.
Snake River Plain - Yellowstone Eruptive Centers
LC = 0.60 Ma Lava Creek Tuff 
MF = 1.29 Ma Mesa Falls Tuff 
HR = 2.00 Ma Huckleberry Ridge Tuff 
H = 4.49 Ma tuff of Heise 
Ek = 5.37 Ma tuff of Elkhorn Springs 
WC = 5.81 Ma tuff of Wolverine Creek 
CC = 5.94 Conant Creek Tuff 
BC = 6.19 Ma tuff of Blue Creek 
W = 6.19 Ma Walcott Tuff 
ES = 6.57 Ma tuff of Edie School 
AF = 7.48 Ma tuff of America Falls 
KC = 9.17 Ma tuff of Kyle Canyon 
LR = 8.75 Ma tuff of Lost River Sinks 
Ch = 9.34 Ma tuff of Little Chokecherry Canyon 
AV = 10.09 Ma and 10.27 Ma tuff of Arbon Valley A & B 
Tw = 8.6 to10 Ma Twin Fall Caldera 
Br-Ja = 10.0 to 12.5 Ma Bruneau-Jarbridge Caldera 
Ow-Hu = ~13.9 to 12.8 Ma Owyhee-Humbolt Caldera 
M = 16.1 Ma McDermitt Caldera