V. S. GEOLOGICAL SURVEY 



MONOGRAPH 55 PLATE XV 



A. SOUTH END OF SHEEP MOUNTAIN, NEAR HEAD OF CORRAL DRAW, BIG BADLANDS, S. DAK. 

 Showing Oreodon zone (Brule formation). Am. Mus- negative 36006 



B. CEDAR CREEK, BIG BADLANDS, S. DAK. 

 Showing Oreodon zone (Brule formation) overlying Titanotherium zone (Chadron formation). Am. Mus. negative 36013 



BRULE AND CHADRON FORMATIONS OF SOUTH DAKOTA 



