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Circular 170—Normapolles pollen from Aquilapollenites Province, western United States

By R. H. Tschudy, 1980, 14 pp., 1 table, 3 figs.

Describes Normapolles pollen usually from northeastern U.S. present in Aquilapollenites province of western U.S., showing that a few genera crossed the seaway barrier between the two provinces. Presents a record of known occurrences of Normapolles in the western province and shows stratigraphic distribution of these occurrences.

During Late Cretaceous time two distinct and geographically separate land floras were present in the northern hemisphere. The areas containing these floras have been named the Normapolles province and the Aquilapollenites province according to the predominant pollen type present. In North America during the Cretaceous, these two provinces were separated by a great north-south-trending epeiric sea that apparently provided a barrier to plant migration until its final withdrawal during the early Tertiary.

Upper cretaceous rocks of the eastern part of North America are characterized by their content of pollen from numerous genera belonging to the Normapolles group. Most of these genera, such as Interporopollenites, Pseudoculopollis, and Endoinfundibulapollis, have never been observed in rocks from western North America. The Aquilapollenites province extends westward from the Mississippi embayment area through the western U.S., Canada, and through Alaska into eastern Asia; the Normapolles province extends eastward from the Mississippi embayment to western Europe. During the Cretaceous, northeastern North America and Europe were apparently joined; the North Atlantic seaway had not yet opened sufficiently to pose a barrier to plant migration. In Eurasia, two provinces were separated by a north-trending arm of the Tethys Sea during much of Cretaceous time; thus, the two provinces were effectively separated by seaway barriers to plant migrations.

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