Named for Charles J. Orth, nuclear chemist at the Los Alamos National Laboratory, New Mexico. Renowned for his precise analyses for elements by neutron activation methods, Orth has engaged in a world-wide search for evidence of impact of extraterrestrial bodies with the earth at the times of mass extinction of species. He discovered noble metal anomalies at the Cretaceous-Tertiary boundary in continental sedimentary deposits of North America and also near the Frasnian-Fammenian boundary in the Upper Devonian and the Cenomanian-Turonian boundary in the Upper Cretaceous. (M 17658) _ _.