First U-Pb zircon ages for late Miocene Ashfall Konservat-Lagerstätte and Grove Lake ashes from eastern Great Plains, USA Smith, Jon J. ; Turner, Elijah ; Möller, Andreas ; Joeckel, R. M. ; Otto, Rick E. Abstract Publication: PLoS ONE Pub Date: November 2018 DOI: 10.1371/journal.pone.0207103 Bibcode: 2018PLoSO..1307103S