^32 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 75 



GooDSiR Formation. Allan, 1914 



The Goodsir formation presents a number of problems of unusual 

 stratigraphic, structural, and faunal interest. 



Dr. R. G. McConnell, in a brief report on his classical reconnais- 

 sance section near the 51st parallel-,' grouped the limestones and 

 shales west of Field into the Castle Mountain group, stating that in 

 the west along the Columbia (Beaver foot Range) it was overlain by 

 the graptolite shales. 



Later, Dr. John A. Allan studied the formations west of Field and 

 proposed the name of Goodsir for a portion of the shales and siliceous 

 limestones of McConnell's Castle Mountain group that occur in the 

 Ottertail Rangie. In his account of the formation, published in 1914," 

 it is described as lying conformably on the Upper Cambrian limestones 

 of the Ottertail formation, with a basal band of soft calcareous red- 

 weathering shales overlain by a band of greenish, dense siliceous shale. 

 These two bands are together about 150 feet (457 m.) thick, and 

 from them, most, but not all, of the fossils found in the typical 

 Goodsir have been collected. He continues : 



Character. — In general the lower half of the Goodsir formation consists at 

 the base of alternating bands of (i) soft argillaceous and calcareous slate, 

 grey and bufif coloured, and forming gentle slopes ; and (2) harder bands of 

 siliceous and dolomitic, siliceous slate weathering fawn and light yellow, and 

 forming steep ledges. This character only holds true in Striped mountain and 

 Beaverfoot valley where the measures though more highly cleaved are less 

 affected by contact metamorphism. In the section on Mt. Goodsir this dis- 

 tinction of alternating hard and soft bands can not be made and the formation 

 consists of cherts, cherty limestone, banded cherts, shales, thin-bedded lime- 

 stones siliceous and dolomitic, interbedded with siliceous shale. The dense 

 compact nature of all the beds and their thin-bedded character are features 

 especially characteristic of the formation in this locality. The colour on 

 weathered surfaces is dark brown, chocolate brown, reddish, purplish, olive, 

 buff, drab, and grey. The general colour of the whole when viewed from a 

 distance is dark brown. On account of their dense, hard character, most of 

 the beds break up into sharp, rectangular fragments, which on further decom- 

 position form sharp edged, rock debris. The uppermost 500 feet [152.4 m.] 

 of the formation in Striped mountain consists of alternating beds like those at 

 the base, but the strata do not tend to outcrop in ledges since the beds in the 

 different bands are of nearly equal hardness. The highest bed is a greenish 

 purple, hard, dense, siliceous limestone that contains numerous lenticular con- 

 cretions of pyrrhotite with some chalcopyrite.^ 



Distribution and thickness. — This formation caps the Ottertail mountains. 

 There are a few square yards exposed on the extreme top of Mt. Hurd ; it 



' Geol. Surv. Canada, Report for 1886 (1887), Pt. D, pp. 24-26 D. 

 ^ Geol. Surv. Canada, Mem. No. 55, 1914, pp. 94-100. 

 ^ Loc. cit., pp. 95, 96. 



