H/gh eros/o/? surface 



RED VALLEY 



HOGBACK 



High terrace 



Fig. 24.11. Generalized cross section of the east front of the Black Hills just south of Rapid 

 City, and cross section of the Ragged Top laccolith. Lower diagram after O'Harra, 1933. Cd, 

 Deadwood fm.; OW, Whitewood Is.; Ce, Mississippian Englewood Is.; Cp, Mississippian Pahasapa 

 Is.; Cm, Pennsylvanian Minnelusa ss.; Pm and Po, Permian Opeche fm. and Minnekahta Is.; "is, 



Spearfish fm.; Js, Sundance fm.; Ju, Unkapapa ss.; Jm, Morrison fm.; Kl, Lakota ss.; Kf, Fuson 

 sh.; Kfr, Fall River ss.; Kgr, Graneros sh.; Kgl, Greenhorn Is.; Kc, Carlile sh.; Kn, Niobrara sh.; 

 Kp, Pierre sh. 



