THE AGE OF THE DOMES AND ANTICLINES IN THE 

 LOST SOLDIER-FERRIS DISTRICT, WYOMING^ 



A. E. FATH 



United States Geological Survey, Washington, D.C. 



INTRODUCTION 



The relative age of the major and minor folding in Wyoming is 

 a somewhat mooted question among geologists, especially among 

 those who are interested in the problems of oil and gas accumulation. 

 In a recent paper BalP reached the conclusion that nearly all the 

 minor folds of Wyoming were formed during the period of formation 

 of the major uplifts. That exceptions to this general rule may 

 exist is frankly admitted by Ball, and he cites the Simpsons Ridge 

 fold as the one example with which he is famihar of an upHft in 

 which the minor folding is clearly younger than most of the major 

 folding. Although agreeing in general with Ball's conclusion, the 

 writer believes that exceptions to the rule are more numerous than 

 Bah suggests. He believes further that a most noteworthy excep- 

 tion to the rule is to be found in the folds of the Lost Soldier- 

 Ferris oil and gas district of south-central Wyoming, the age 

 relations of which are here discussed. 



GEOGRAPHIC AND GEOLOGIC RELATIONS 



The Rawlins uplift, in south-central Wyoming, is about fifty 

 miles in length and twenty miles in width and trends in a northerly 

 direction (see map). It is not large enough to be classed among 



^ Published with the permission of the Director of the United States Geological 

 Survey. The information presented in this paper was obtained in the summer of 

 1920, during an examination made to obtain data for classifying the public land in 

 the oil and gas fields of the Lost Soldier-Ferris district. The results of this examina- 

 tion are being prepared for publication by the United States Geological Survey. 



= Max W. Ball, "The Relative Ages of Major and Minor Folding and Oil 

 Accumulation in Wyoming," Amer. Assoc. Petroleum Geologists, Bull. 5 (1921), No. i, 

 pp. 49-63. 



303 



