YAKINIKAK LIMESTONE 325 



stone, it was assumed that strata of that age would be found in the sec- 

 tion near the 49th parallel, but in the Lewis and Livingston ranges 

 nothing which could be referred to the Carboniferous system was ob- 

 served. Dawson's correlation of the Siyeh limestone as Carboniferous 

 has already been discussed. On crossing the Flathead valley, however, 

 to the Galton range, which lies between North fork of the Flathead and 

 Kootenai rivers, a small area of limestone was encountered in Yakinikak 

 valley. The rock is a light gray and dark blue limestone about 100 feet 

 thick, distinctly bedded, commonly crystalline, occasionally oolitic. 

 Some fractures have a black, speckled appearance due to dark cleavage 

 faces on calcite crystals. It is without upper stratigraphic limit, but 

 rests conformably on a quartzite, which is unconformable on Algonkian 

 strata. The quartzite is about 25 feet thick, and it and the limestone lie 

 in a nearly horizontal position- The name Yakinikak is here applied to 

 the limestone, exclusive of the quartzite, which may elsewhere develop 

 independent importance. 



The Yakinikak limestone contains numerous fossils of the Saint Louis 

 horizon of the Mississippian series, and was fully identified by Weller as 

 identical in lithologic character and faunal content with that formation 

 in the Mississippi valley. Its occurrence on Yakinikak creek is appar- 

 ently due to down-faulting, as it lies at a comparatively low level among 

 mountains composed of the Algonkian argillites. Its presence in this 

 locality, taken in connection with other occurrences north and south 

 may be considered evidence of the former extension of the upper Missis- 

 sippian limestone over the entire region. The absence of the earlier Mis- 

 sissippian strata is significant of an unusual overlap. 



In the course of a report of explorations in 1901 * for coal on Wigwam 

 river Mr W. W. Leach, of the Canadian Survey, refers to the " Devono- 

 Carboniferous limestones of the MacDonald range, a high and extremely 

 rugged group of mountains which forms the divide between Wigwam 

 and Flathead rivers." The Yakinikak limestone lies at the southern 

 extremity of the MacDonald range, which may be said to die out at the 

 49th parallel, and it is probable that its fossiliferous strata make up the 

 heights farther north. It is also possible that it rests on Siyeh lime- 

 stone, in which case the break between the two would not be readily 

 recognized, as the rocks are very similar and the angular difference of 

 dip is slight. 



TBI a ssi c 



Dawson's report for 1885 and the accompanying map represent cer- 

 tain rocks of the Livingston range near the South Kootanie pass as Tri- 



* Summary Report, Geological Survey Department of Canada, 1901, p. 72. 



