Normapolles pollen from Aquilapollenites province, western United States

Abstract

During Late Cretaceous time in North America, two distinct land floras were present, one in the Normapolles province in northeastern North America and one in the Aquilapollenites province in the western part of the continent. A few fossil pollen grains assignable to Normapolles genera have been found in formations of the Western Interior of the United States. These formations lie within the Aquilapollenites pollen province. Pollen types found in Upper Cretaceous and lower Tertiary rocks from the Normapolles province and from the Aquilapollenites province generally are distinctly different. During Late Cretaceous time the two provinces were isolated from each other by epeiric seaway barriers to plant migration. The presence of Normapolles-type pollen in rocks of the Aquilapollenites province demonstrates that at least a few Normapolles genera were able to surmount this seaway barrier. A record of the presently known occurrences of Normapolles genera in the Aquilapollenites province of western North America is presented together with the stratigraphic distribution of these occurrences. Some Normapolles genera from the west have been shown to be of aid in the recognition of specific segments of the stratigraphic column. Others appear to be present only in the northern or southern part of the Aquilapollenites province, and still others have been found so infrequently that they are of minor stratigraphic significance.