BULL. GEOL. SOC. AM. 







VOL. 15. 1903, PL. 25 







|i ■lyii.iuii^^ 





'■— ■ v '■'#!T'-«2 B ^BHi 



• 



^^W 1 '-s~^^ 



^ ^is^ 





' " ■! 1 ^Ti 



HBBbj.-. ,^ 1 ^^ kM L^ih T-fl 





■■KTt 



'. 'i»hjw; 







- 







Figure 1.— Gypsum Deposits in Spearfish Kkd Bkds, near Hot Springs, South Dakota 



Figi ki. 2. Massive Sandstone at Base of Sundance Formation 

 Lying unconforinably on red shales of Spearfish formation 



SPEARFISH RED BEDS AND OVERLYING MASSIVE SANDSTONE 



