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Sherbrooke Formation. — Arenaceous limestone at 

 the base of this formation is overlain by thin-bedded 

 limestone, including some oolitic and shaly layers. This 

 formation includes the highest beds exposed in the Bow 

 Range in the vicinity of Hector Pass. 



The remaining Cambrian formations, the Ordovician, 

 and the Silurian are all exposed in the western portion of 

 the section between the Bow range and Columbia 

 valley. 



Chancellor Formation. — This formation consists essen- 

 tially of shales which weather reddish, yellowish, fawn or 

 gray. The uppermost 2,500 feet (762 m.) are gray met- 

 argillites, well cleaved along the bedding planes, and 

 weathering reddish and yellowish. These shales become 

 much more highly cleaved towards the base of the forma- 

 tion, so that the lowermost, 2,000 feet (610 m.) thick, 

 consist chiefly of phyllites and slates, with argillites and 

 a few interbedded layers of shaly limestone. The fer- 

 ruginous content in all the beds is high, so that the weather- 

 ed surface is usually reddish or yellowish. This series 

 floors Ottertail valley, underlies the Ottertail range, and 

 makes up a large part of the Van Home range. 



Ottertail Limestone. — This formation consists almost 

 entirely of blue limestone, massive towards the top and 

 rather thin-bedded towards the base. It has a thickness 

 of over 1,725 feet (526 m.) in the Ottertail range, where 

 it is well exposed in an almost perpendicular escarpment 

 along the east side of the range. The cliff-forming char- 

 acter of this formation marks it off very sharply from the 

 shale formations below and above. 



This limestone represents the highest series in the 

 Cambrian in this portion of the Rocky mountians. 



ORDOVICIAN. 



Goodsir Shales. — This formation is best exposed in 

 Mt. Goodsir, where it has a measured and estimated 

 thickness of over 6,040 feet (1,841 m.). It lies conformably 

 on the Ottertail limestone and consists at the base of 

 almost 3,000 feet (914 m.) of alternating hard and soft 

 bands of argillaceous, calcareous, and siliceous shale, 

 which weather light yellowish, gray and buff. 



The upper part of the formation consists of banded 

 cherts, cherty limestones and dolomites, thin-bedded and 



