NO. 5 PRE-DEVONIAN PALEOZOIC FORMATIONS 239 



west of the Kicking H'orse River the Ottertail formation may extend 

 is unknown. 



Stratigraphic relations. — These have been described by Allan as 

 follows : 



The upper and lower contacts of the formation are everywhere sharply 

 marked and can be located, especially when viewed from a short distance, 

 within a few feet. At the lower contact are the red weathering beds of the 

 Chancellor formation, while at the upper contact is another thin-bedded slaty 

 series very distinct in character from the more resistant blue limestone of the 

 Ottertail formation. This formation is, therefore, a unit, and can almost 

 always be readily distinguished from the overlying and underlying formations 

 and forms a good horizon marker. 



Organic remains. — Allan found many fragments of fossils among 

 which only two genera could be provisionally identified — Lingulella, 

 and cranidia of a small trilobite that belongs to some one of the 

 genera to which are now being referred American forms heretofore 

 referred to Ptychoparia. 



In a band of gray limestone, made up of layers from 3 inches 

 (7.6 cm.) to 30 inches (76.2 cm.) in thickness, that occurs about 

 200 feet (60.9 m.) from the base of the Ottertail formation at Wol- 

 verine Pass, Mrs. Walcott and I found many fragments and a number 

 of nearly entire trilobites. The fauna (Loc. 63X) contains Obolus 

 myron Walcott, Lingulella siliqua Walcott, and a trilobite belonging 

 to an undescribed genus that appears to be related to Kainella. 



Observations. — The Ottertail formation is clearly defined by its 

 lithologic characters and fauna and by an easily recognized line of 

 demarcation at both base and summit. Its fauna as far as known is 

 quite distinctive, and as it is overlain by Upper Cambrian, it may also 

 be placed in that division. 



The limestones and calcareous shales composing the formation are 

 more of the type of those of the superjacent Goodsir formation than 

 of any other formation either in the Goodsir or Beaverfoot Troughs. 

 Mr. J. F. Walker has correlated the thick-bedded, rough-weathering 

 arenaceous and magnesian limestones beneath the Sabine formation 

 in the Stanford Range in Sinclair Canyon, at the mouth of Stoddart 

 Canyon, and along the range to the south as far as Sabine Mountain, 

 with the Ottertail formation, but in my judgment, this correlation 

 is not supported by lithologic, stratigraphic, or paleontological evi- 

 dence. I will speak of this more fully luider the Lyell formation 

 (p. 228). 



