BULL. GEOL. SOC AM. 



VOL. 13, 1901, PL. 47 



Figure 1.— Margin of Great Plains at Foot of Lewis Range 

 Looking south across Swift Current valley to Saint Mary ridge and East Flattop 



Figure 2. — North Side of Swift Current Valley near Altyn 

 Looking east. Typical Altyn limestone cliff, lower member, overlying Benton shale. Locality of Algonkian fossils 



MARGIN OF GREAT PLAINS AND NORTH SIDE SWIFT CURRENT VALLEY 



