Ion microprobe U-Pb zircon age results for the Bishop Tuff (Long Valley; Reid and Coath, 2000) and La Pacana (Schmitt et al., 2002) argue strongly against protracted preeruptive magma storage.By contrast, Long Valley post-caldera lavas show evidence for >100 ka crystal residence (Reid et al., 1997) and remelting of solidified and hydrothermally altered precursor intrusions …