Footnote 4 – Exploring the Deep

John P. Oleson’s study of this material indicates that it comes from North Africa as well as Italy; see Robert D. Ballard, Anna Marguerite McCann et al., “The discovery of ancient history in the deep sea using advanced deep submergence technology,” Deep-Sea Research I, vol. 47, no. 9 (2000), pp. 1612–1614.