NO. 6 



SMITHSONIAN' EXTLORATIOXS, I92O 



Early in July work was begun along Ghost River northeast of 

 Banff and about 53 miles ( S5 km.) west of Calgary. Alberta. The 

 route taken was along the north shore of Lake Minnewanka (fig. i, 

 Frontispiece) and through the Devils Gap to Ghost River. Avhich here 

 runs north and south at the foot of high eastward-facing cliff's of 

 Cambrian limestone, capped by limestones of Devonian age. Lake 

 IMinnewanka is a l}eautiful sheet of water (fig. 2) in the broad 

 bottom of a pre-glacial river channel, the eastward extension of which 

 forms the Devils Gap. 



The Rocky ^lountain front (fig. 3) is formed of masses of evenly 

 bedded limestone that have been pushed eastward over the softer 

 rocks of the Cretaceous plains-forming rocks. This overthrust is 

 many miles in extent and r)ccurred long ago before the Devils Gap, 



Fig. 5. — Devils Head 19,204 lt.>, a butte rising aljove tlie cliffs of Fig. 3 on 

 the north side of Ghost River Gap. Photograph hy C. D. W'alcott. 1920. 



Ghost River Gap and other dpenings were cut through the cliffs by 

 running water and rivers of ice. Great headlands ( fig. 4 ) and high 

 buttes (fig. 5) have been formed by the silent forces of water and 

 frost, many of which stand out against the western sky as seen from 

 the distant foothills and plains. 



It was amr)ng the.se cliffs that we found that the first great cliff 

 (figs. 3 and 4) was of lower Middle Cambrian age. and that resting 

 on its upper surface there were 2i^^ feet (86 m. i of a yellowish 

 weathering magnesian limestone, here named the ( iho.-<t Kivcr forma- 

 tion, which represents the great lost interval between the Cambrian 

 below and the Devonian above. .Sixty miks to the west, over four 

 miles in thickness of limestone, shales and sandstones ( 22.6-0 feet 

 (6,890 ni.)), occur in the lost interval of the ( ihost River cliffs. 



