POST-CRETACEOUS HISTORY OF WESTERN WYOMING 319 



miles wide at the type locality, but were much broader near Fort 

 Washakie and Lander. In the somewhat more remote headwaters 

 of the Gros Ventre valley, the terraces are only a fraction of a mile 

 in breadth. They are distinctly older than the latest (Pinedale) 

 stage of glaciation. The older (Bull Lake) moraines, however, rest 

 upon the Circle terraces and blend into them in such a way as to 

 indicate that the terraces were parts of the floodplains in the earlier 

 glacial stage. 



Fig. 37. — Circle terraces along North Fork of Owl Creek. Bedded Tertiary 

 volcanics in the background. 



Lenore cycle: Following the last distinct rejuvenation, the 

 inner trenches of Wind River and its tributaries were excavated in 

 the Circle floodplains (Figs. 39, 40). Although these valleys are 

 relatively narrow in their upper reaches, they are well graded, and 

 the floodplains are broad enough locally to accommodate ranches, 

 as at Lenore and Circle. They expand considerably downstream. 



Farther west in the Gros Ventre vafley there is a similar inner 

 valley cut in the well-defined terrace of the Circle cycle. Fish 

 Creek has intrenched the Circle plain to a depth of 100-150 

 feet, and then by meandering has developed a floodplain about 

 1,000 feet wide (Fig. 41). On the whole, the valleys are consid- 

 erably narrower here than in the Wind River basin, but the rocks 



