The thesis of this paper is as follows: It is proposed to show that the dinosaur-bearing beds known as “Ceratops beds,” “Lance Creek beds,” Lance formation, “Hell Creek beds,” “Somber beds,” “Lower Fort Union,” Laramie of many writers, “Upper Laramie,” Arapahoe, Denver, Dawson, and their equivalents, are above a major unconformity and are Tertiary rather than Cretaceous in age.

As this is essentially a stratigraphic problem and not, as some assume, an exclusively paleontologic one, a certain amount of structural data are necessary as a setting for the paleontology. It is proposed, therefore, first, briefly to present the evidence on which this unconformity is predicated.


The geological formations here involved are spread widely over the States of New Mexico, Colorado, Wyoming, the Dakotas, Montana, and adjacent Canadian territory. It is held that the dinosaur-bearing beds above mentioned are separated from underlying beds by a major unconformity which . . .

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