BULL. GEOL. SOC. AM. 



VOL. 12, 1900, PL. 14 



Fkjukk 1.— S.^M) 1\(>( k on I>kvii, Hir.i, 

 Coiiijiosed (if l:irg(' r;iili:itiiii!; saiul-limf ooncictioiis 





FjlilUK -J. — POUTIUN (IF GUKAT Pll'K 



SAND ROCK AND PORTION OF GREAT PIPE, DEVIL HILL, SOUTH DAKOTA 



