BULL. GEOL. SOC 



K...lucmi l'1-l.lil Hn.wllilll; :HI.I Chief Mnltllh 



MAP OF GREAT PLAINS AND FRONT RANGES, NORTHWEST MONTANA 



0". S. Geological survey, shaded area, Cretaceous rocks; white area, Algonkian rocks ; heavy 1 



mountain to North Fork valley see plate 5:1. 



uutcrop ol' Lewis thr 



