Discussion of Carboniferous Papers
Mackenzie Gordon, Jr.2—The use of the provincial series names Rundlian-Banffian, etc., seems very desirable, as correlation of the beds in this region with those of Mid-Continent of the United States is difficult. Now that the U. S. Geological Survey has raised the Mississippian and Pennsylvanian to systems, we are confronted with the problem of subdividing them. There appears to be no single set of series that will fit the whole country. It is desirable, therefore, to have provincial series.
Some of the zone fossils selected for the Canadian section in this paper have long ranges in the United States. For example Leptaena analoga in the Mid-Continent occurs throughout the Kinderhook and into the basal Osage; in the west it ranges all the way through the Madison group, which may extend higher into the Osage. At one locality it ranges up into the Brazer. In Texas it has been reported to be associated with grimesi-type spirifers and with goniatites of Meramec-Chester age.
Spirifers are difficult to use as zone fossils. S. increbescens is said to be typical of a zone in the lower part of the upper Chester rocks of Alberta, with S. leidyi occurring above it. However, in some sections in the United States leidyi-like spirifers range well down into the Meramec and well up through the Chester. S. increbescens seems to be confined to the Chester. In the Big Snowy group in Montana according to an unpublished work by Easton, S. increbescens is one of the highest