36 n r . Cross — Post-Laramie Deposits of Colorado. 



succession of several thousand feet of strata in this region has 

 been referred to the Laramie, but Major Powell claims to have 

 found an important physical break below the horizon contain- 

 ing the Agathaumas, as he expressly states,* and if this is true 

 this Dinosaur may actually occur here in strata contempora- 

 neous in time with the Arapahoe beds. In any case it remains 

 to be proven that the "Ceratops beds " of Marsh, from the 

 " eastern base of the Rocky Mountains " are stratigraphical 

 equivalents of the horizon at Black Butte in which the Agath- 

 aumas was found. 



This brings us to the questions : On what ground does 

 Prof. Marsh assign the Ceratops beds to the Laramie ? and, 

 What does the Laramie properly embrace ? The assignment 

 rests, as far as published evidence goes, on the presence of a 

 new fauna of strong Mesozoic affinities, in beds more recent 

 than the Fox Hills, and unknown, with the possible exception 

 noted above, in strata known to occupy the stratigraphical po- 

 sition assigned to the Laramie in its original definition. The 

 general statement of Prof. Marsh that the Ceratopsidre he has 

 described " are found in the typical Laramie of Wyoming " is 

 misleading in this sense, that, to any one acquainted with the 

 literature of the subject, " the typical Laramie of Wyoming " 

 must always be that formation in southwestern Wyoming to 

 which Mr. Clarence King first applied the name, or its demon- 

 strated equivalent. And it seems opportune to quote here the 

 definition of the Laramie given by that author. After explain- 

 ing, that on consultation with Hayden and without compro- 

 mising differences of opinion as to the age of the beds in 

 question, a common name had been adopted, he says : " Ac- 

 cordingly ... it was amicably agreed between us [Hayden 

 and King] that this series should receive the group name of 

 Laramie, and that it should be held to include that series of 

 beds which conformably overlies the Fox Hills." f Experi- 

 ence since this definition was set up has shown that over a 

 very large area there is a great and important formation to 

 which that definition strictly applies. And evidence continu- 

 ally accumulates to prove that this formation, which certainly 

 must be called the Laramie, was the last of the series of con- 

 formable deposits belonging to the Cretaceous. 



Returning to the question as to the evidence concerning the 

 stratigraphical position of the " Ceratops beds," it is to be 

 noted that in Montana and Wyoming they are said to occur on 

 the eastern flank of the Rocky Mountains, in a district which 



* Geology of the Uinta Mountains, p. 72. 



f Final reports of the Fortieth Parallel Survey, vol. i, Systematic Geology, 

 p. 331. 



