EPOCHS SEPARATING THE GROUPS. 05 



geophila ; and brackish water fossils, in perhaps a very few instances of the 

 same species with those below, are associated with fresh water fossils ; hence 

 the change from marine to fresh water conditions seems not to have been 

 abrupt. 



It will be noted that the epochs of change which separate the fresh 

 water Cenozoic groups all represent a change in character of the sediments, 

 and also represent more or less abrupt contraction of the expanse of fresh 

 water. This was very great during the Bitter Creek period ; somewhat 

 less during the Lower. Green River; somewhat less during the Upper; 

 perhaps about, the same, but less in some directions and greater in others, 

 during the Bridger ; and when we reach that point of time represented by 

 the Brown's Park beds the area was quite small. 



Those beds to which the name Wasatch Group has been given, and 

 which are found on the eastern slope of the Wasatch Mountains, and 

 stretching out to the eastward until they run under Lower Green River 

 beds, are the western extension of the Bitter Creek beds, and hence the 

 name Wasatch Group should be dropped. The conglomerate at the 

 bottom of what was called the Wasatch Group is represented by the con- 

 glomerates of the Bitter Creek Group on bo'Ji flanks of the Uinta Mount- 



6 



ains. 



The beds called the Washiki Group are the upper part of the Bitter 

 Creek series. I have been unable to carry any line of demarkation 

 between these beds over such an extent of country as would warrant their 

 separation from the Bitter Creek series, yet this may be done, and in such 

 a case the name of Washiki Group should be retained. In the region near 

 Washiki Station, where they were first seen by Dr. Hayden, they are 

 exceedingly conspicuous by reason of their brilliant colors. Professor 

 Cope, who saw them a little farther to the southwest, thus appropriately 

 describes them: "Several miles to the south we reach another bench whose 

 bluffy face rises four or five hundred feet in buttress-like masses, interrupted 

 at regular intervals by narrow terraces. This line is distinguished by its 

 brilliantly colored strata, extending in horizontal bands along the escarp- 

 ment. They are brilliant cherry-red, white, true purple with a bloom- 

 si lade yellow and pea-green, forming one of the most beautiful displays I 

 5 P G 



