In his Discussion of the paper by Dill et al.(2007), Romer (2008) proposes an alternative explanation for U-Pb data of limonite enclosed in Pliocene torbernite. According to Romer (2008), limonite formed shortly after Carboniferous columbite and its U-Pb system was perturbed by the loss of intermediate daughters from the 238U decay series subsequent to their dislocation near to grain boundaries by α-recoil. The 206Pb/238U and 207Pb/235U ages >300 Ma are explained by U-loss in limonite during torbernite formation. In the model advocated by Romer (2008), both processes in...

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