4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 134 
ACKNOWLEDGMENTS 
I am deeply grateful to J. D. Love for guidance and inspiration dur- 
ing the field investigations, which were carried out under his supervi- 
sion. His knowledge of deposits of Tertiary age in Wyoming and the 
geology of that State, freely shared, enabled me to place concepts 
developed from observations in the northeastern part of the Wind 
River Basin within the framework of the regional geologic history. 
G. Edward Lewis aided greatly during the fieldwork by supplying 
prompt identifications of fossil vertebrates submitted to him for study 
and by participating in many helpful discussions of stratigraphic 
problems. The enthusiasm and constant encouragement of Dr. Gazin 
have aided much in the preparation of this report. E. B. Wasson 
assisted in the fieldwork in 1945 and R. A. Christman in 1947; both 
were able and pleasant field companions. I am indebted also to the 
residents of the area for many helpful courtesies. Particular men- 
tion should be made of Mr. and Mrs. R. W. Spratt, Mr. and Mrs. 
Frank Rate, and Mrs. William Twidale and the late Mr. Twidale. 
STRATIGRAPHY 
THE WIND RIVER FORMATION 
The Wind River formation is divided into the Lysite and Lost 
Cabin members, each of which consists of two facies. The members 
are differentiated on the basis of the composition of roundstones in 
the conglomerate beds and the colors of the fine-grained beds. The 
two members have been distinguished only in the area east of the 
west line of R. 91 W. In other areas, such as the remainder of the 
Wind River Basin, the Big Horn Basin, and elsewhere, the two names 
are used only to identify faunal zones, the younger of which, the Lost 
Cabin, is characterized by Lambdotherium (Sinclair and Granger, 
1911; Van Houten, 1945). 
The Lysite member, the oldest part of the Wind River formation 
exposed in the northeastern part of the Wind River Basin, consists 
of orange-red and yellowish-gray variegated siltstone with beds of 
tan to brown fine-grained to conglomeratic sandstone and some boul- 
der conglomerate. The boulder conglomerate is exposed near the 
center of T. 39 N., R. 89 W., in the northwest part of Cedar Ridge. 
Rock pieces as large as 2 feet in diameter are common, and excep- 
tional pieces are as much as Io feet in maximum diameter. Con- 
glomeratic sandstone along Cottonwood Creek, near the fault that 
separates the Wind River formation from the strata of middle(?) 
