d234U = ([234U/238U]activity - 1)x1000.d234Uinitial was calculated based on 230Th age (T), i.e., d234Uinitial = d234Umeasured x e**l234xT.Corrected 230Th ages assume the initial 230Th/232Th atomic ratio of 4.4 ±2.2 x10-6. Those are the values for a material at secular equilibrium, with the bulk earth 232Th/238U value of 3.8. The errors are arbitrarily assumed to be 50%.B.P. stands for "Before Present" where the "Present" is defined as the year 2000 A.D.