Lee — Recent Discovery of Dinosaurs in the Tertiary. 531 



Art. XLV. — Recent Discovery of Dinosaurs in the Ter- 

 tiary ;* by W. T. Lee. 



The fossils forming the subject of this paper were found 

 about nine miles east of Colorado Springs, Colorado, south of 

 Jimmy Camp Creek, in sec. 3, T. 14S., K. 65 W., about 500 

 feet above the base of the Dawson arkose (the lower part of 

 the Monument Creek formation of former writers). Geol- 

 ogists since the time of Hayden have referred these beds to 

 the Tertiary, and liichardsonf has recently added much to our 

 knowledge of them, strengthening their reference to the Tertiary 

 by showing that they are conspicuously unconformable with 

 the Laramie and that they contain a large flora which, accord- 

 ing to Knowlton, is essentially the same as that of the Raton 

 formation;); or the oldest Tertiary of the Raton Mesa region 

 and with that of the Eocene Wilcox formation of the Gulf 

 Coast. Richardson has also shown to the satisfaction of many 

 geologists that the lower part of the Monument Creek, which 

 he has called Dawson arkose, is the stratigraphic equivalent of 

 the Denver and Arapahoe formations of the Denver Basin. 

 This equivalency is confirmed by the fossil plants, inasmuch as 

 those from the Dawson arkose belong to the Denver flora. 

 The subject will be presented by Richardson more fully in the 

 Castle Rock folio, now in course of preparation. 



Geologists will recall that the Denver and Arapahoe forma- 

 tions have long been known to contain the Ceratopsian dino- 

 saurs which originally furnished the grounds for retaining 

 these formations in the Cretaceous even though they were 

 known to contain an Eocene flora and to be separated from the 

 underlying Cretaceous by an unconformity that, according to 

 Emmons,§ marks " unquestionably one of the most important 

 events in the orographical history of the entire Cordilleran 

 system." Some geologists did not agree with this disposition 

 of the formations but were overruled, and Cross || has recently 



* Published by permission of the Director U. S. Geological Survey. 



f Richardson, G. B. : The Monument Creek group, Geol. Soc. America, 

 Ball., vol. xxiii, pp. 267-276, 1912. 



X Raton formation is the name recently adopted by the U. S. Geological 

 Survey for the coal-bearing rocks above the unconformity in the Raton Mesa 

 region of southern Colorado and northern New Mexico. Those below the 

 unconformity have been named Vermejo formation. The two constitute what 

 has heretofore been called Laramie in this region. The data upon which 

 they were separated are contained in a forthcoming paper by W. T. Lee and 

 F. H. Knowlton, on the Raton Mesa Region, which will be published by the 

 U. S. Geological Survey. 



§ Emmons, S. F.: Orographic Movements in the Rocky Mountains, Geol. 

 Soc. Amer., Bull., vol. i, p. 285, 1890. 



|| Cross, Whitman: The Laramie formation and the Shoshone group, Wash- 

 ington Acad. Sci., Proc, vol. xi, p. 4.2, 1909. 



