[On June 30, 2009, IUGS ratified ICS Recommendation on redefinition of Pleistocene and formal definition of base of Quaternary. The pdf-format letter from IUGS is attached here.]

June 30, 2009

Prof. Paul R. Bown,
Secretary, International Commission on Stratigraphy (ICS)
Department of Geological Sciences
University College London
Gower Street
London WC1E 6BT
United Kingdom

RE: Ratification of the definition of the base of Quaternary System/Period (and top of the Neogene System/Period), and redefinition of the base of the Pleistocene Series/Epoch (and top of the Pliocene Series/Epoch).

Dear Professor Bown,

This is to confirm the receipt of your Commission’s request of June 2, 2009 for ratification of its recommendation that:

1) the base of the Pleistocene Series/Epoch be lowered such that the Pleistocene includes the Gelasian Stage/Age and its base is defined by the Monte San Nicola GSSP, which also defines the base of the Gelasian;

2) the base of the Quaternary System/Period, and thus the Neogene‐Quaternary boundary, be formally defined by the Monte San Nicola GSSP and thus be coincident with the bases of the Pleistocene and Gelasian, and

3) with these definitions, the Gelasian Stage/Age be transferred from the Pliocene Series/Epoch to the Pleistocene.

I am pleased to report that these recommendations were approved by a majority vote of the IUGS Executive Committee on 29 June 2009.

Sincerely yours,

Prof. Alberto C. Riccardi

President
International Union of Geological Sciences

cc: Stan Finney, President, ICS
     Shanchi Peng, Vice President, ICS
     IUGS Executive Committee