340 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 57 



UNCONFORMITY BY EROSION 



PRE-CAMBRIAN 



BELT SERIES, MIETTE FORMATION.— Massive-bedded gray sand- 

 stones with thick bands of gray and greenish siliceous shales. . 2,000-}- 



The best exposures seen of the Belt series were along both 

 sides of Yellowhead Pass from the vicinity of Grant Brook 

 on the west to Fitzhugh on the east. 



In the Yellowhead Pass the cuts of the Grand Trunk Pacific and 

 the Canadian Northern railroads afford fine sections of the Miette 

 sandstones and shales. Some of the layers of sandstone are clean 

 and fresh, but most of the rock suggests deposition of the sand in 

 muddy water. 



It may be that more than one formation occurs in the Belt series, 

 but without detailed study and mapping it will be difficult to de- 

 termine the limits to be assigned to the strata provisionally grouped 

 in the Miette formation. 



On both the north and south sides of Yellowhead Pass the Miette 

 formation occurs in rounded, wooded ridges that rise over 2,500 

 feet (754 m.) above the Pass. To the north the Cambrian of 

 McEvoy Mountain rises as great castelated masses on the northwest 

 side of Miette River, and on the west side Hutam Mountain forms 

 an outlying butte of Cambrian sandstone and limestone. 



To the south of the Pass the banded cliffs of Cambrian rocks in 

 Mount Fitzwilliam and Mount Pelee rise high above their base of 

 Miette sandstones. 



At the Pass the valley is essentially the same type as the valley of 

 Bow River near Laggan. In both, the valley is eroded in the Belt 

 series of impure sandstones and the Cambrian sandstones and lime- 

 stones form high, bold mountains to the north and south of the valley. 



