Improved age estimates for the White River and Bridge River tephras, western Canada

New 14 C ages date the eruptions that produced the White River and Bridge River tephras, two important Holocene marker beds in western Canada. The 14 C ages were obtained on trees in growth position buried in coarse tephra and a pyroclastic flow near the source vents. The mean calendric age of the White River eruption, based on four 14 C ages, is 1147 cal years BP (calibrated years, approximately equivalent to calendric years) or AD 803 (the 2σ age range, obtained from the two most precise 14 C ages, is 1014–1256 cal years BP or AD 694–936). The mean age of the Bridge River eruption, determined both from (i) the single most precise outer-ring 14 C age and (ii) the weighted mean of six outer-ring 14 C ages is 2360 cal years BP or 411 BC (2σ age range = 2349–2704 cal years BP or 755–400 BC).