Jan P. Amend (1) & D'Arcy R. Meyer-Dombard (2)
(1) Departments of Earth Sciences and Biological Sciences, Uni- versity of Southern California, Los Angeles, CA 90089, USA.
(2) Department of Earth and Environmental Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA.
Corresponding author e-mail: janamend@usc.edu