Comparison of the Poronai Formation in the Ashibetsu District with that in the Yubari District, Ishikari Coal Field, Hokkaido

Abstract

Recently, the Poronai formation (which develops) in the Kamiashibetsu district in the northeastern part of the Sorachi coal field has been correlated by some geologists with the upper-most part of the same formation in the Yubari coal field, on the basis of foraminiferal fossils.
But, the writers are inclined to believe that the former should be correlated with the lower part of the latter, according to the mega fossil assemblage and lithological features (examined).