Hartung's article, Harris's reply, and the two subsequent replies by each author represent an experiment for the Journal of Geophysical Research-Planets. The subject area is controversial, and rapid convergence cannot be expected. Already, 13 months have been consumed in the review and rebuttal cycle. Rather than to continue working toward convergence, and having each reply refereed, I have chosen to publish the last two disagreements for the readers. This will not become a usual mode for publication in this journal, but I solicit readers' comments about the potential utility of this mode in some similar cases. In this instance, Hartung's original paper received one favorable review; the other review was converted into Harris's formal reply, which itself was reviewed. ¿ American Geophysical Union 1992