… at the 2200 BC megadrought . Publications: Harvey Weiss 2017 “Megadrought, Collapse and Causality,” in H. Weiss, ed., … . Oxford University Press. Pp. 1- 31. Harvey Weiss 2017 “4.2 ka BP Megadrought and the Akkadian Collapse,” in H. … 93-160. Amy Styring, Mike Charles, Harvey Weiss, et al. 2017 “Isotope evidence for agricultural extensification …