242 smithsonian miscellaneous collections vol. 75 



Sherbrook Formation. Walcott, 1908^ 



Type locality. — West spur of Mount Bosworth, east and above 

 Sherbrook Lake, northwest of Hector Station on the Canadian Pacific 

 Railway. 



Derivation of name. — From Sherbrook Lake. 



Character and thickness. — Massive-bedded, gray and bluish-gray 

 limestone with more or less chert in the upper 285 feet (86.9 m.), 

 superjacent to 190 feet (57.9 m.) of oolitic gray limestone, beneath 

 which greenish-drab and gray siliceous shales, with interbedded, oolitic 

 layers, extend for 335 feet (102.1 m.). Below this, a belt of gray 

 oolitic limestone 65 feet (19.8 m.) thick is superjacent to 610 feet 

 (185.9 m.) of arenaceous, dolomitic, steel-gray limestone. The total 

 thickness is 1,485 feet (452.6 m.). 



Geographic distribution. — The Sherbrook as a distinct formation 

 is known only in the \vestern part of Mount Bosworth. It has not 

 been traced to the east, northwest, or north, unless the Sullivan forma- 

 tion of the Glacier Lake section represents it. 



Stratigraphic relations. — On Mount Bosworth the gray limestones 

 of the Sherbrook are usually clearly separated from the subjacent 

 dark bluish-gray limestones of the Paget, but in some sections it is 

 difficult to recognize a distinct line. The Chancellor shales are re- 

 ported by Allan as superjacent to thick-bedded limestones in the Van 

 Horn Range which he correlated with the limestones of the Sher- 

 brook formation of the Mount Bosworth section. As far as known 

 to me this correlation was a theoretical one, based on the occurrence 

 of a " massive limestone " beneath the Chancellor shales 2 miles 

 (3.2 km.) east of Leanchoil Station on the Canadian Pacific Railway. 



Fauna. — The known fauna is limited to a few species from the 

 middle and upper parts of the section. It includes Lingulella isse 

 Walcott from the shales, and fragments of trilobites, including Crepi- 

 cephalus, from the limestone. 



The Sherbrook fauna is closely related to the Crepicephalus fauna 

 that occurs in the lower portion of the Upper Cambrian of Missouri 

 and in Patterson Canyon, Snake Range, Nevada. It is to be correlated 

 with the upper portion of the Eau Claire formation of Wisconsin. 



Paget Formation. Walcott, 1908'' 



Type locality. — Paget Peak, and western slope of Mount Bosworth 

 on the Continental Divide. 



Derivation of name. — From Paget Peak. 



' Smithsonian Misc. Coll., \'ol. 53, No. 5, 1908, p. 204. 

 ' Idem, p. 205. 



