Reply [to “Comment on ‘That Dahm layer’”]

It is gratifying to see insightful comments from distinguished members of our community about my plea to rename the D″ (double prime) [Eos Trans., AGU, 81, p.46, 2000]. Professors Ben Howell and Carl Kisslinger both point out an interesting slice of history that illuminates this discussion. They correctly mention that while the presently adopted name D″ originated with Keith Bullen's papers of the 1940s, the original description of this internal boundary should be credited to Cornelius Dahm's 1934 Ph.D. dissertation at St. Louis University. It is unfortunate that, instead, Bullen's nomenclature became widely accepted. We can speculate that Bullen was not aware of Dahm's work, something not uncommon in the early days, although unimaginable in today's Internet information age. The original purpose of my note was a suggestion that we rename the D″ layer. We can consider calling it the Dahm layer or Dahm-Bullen layer.