It has long been evident that writers on glacial geology are not at
one concerning some of the important questions which underlie the
interpretation of the history of the glacial period. Certain recent
publications have served to emphasize the differences between them.
There are two questions, at least, concerning which there must be
agreement, or at any rate a common understanding, before existing
differences can be eliminated or justly evaluated. When the answers
to these questions have been agreed upon, or when the positions of
the contending parties are clearly understood, it may be found that
some of the apparent antagonisms have no better basis than differences
in definition. Stated interrogatively, the two questions referred to
are these: 1. What constitutes a glacial epoch as distinct from other
glacial epochs? and 2. What are the criteria for the recognition of
distinct glacial epochs, if such there were?