316 



B. WILLIS LEWIS AND LIVINGSTON RANGES, MONTANA 



Carboniferous -J 



f Limestone, light gray to dark gray blue, 

 crystalline, specked with black cleav- 

 age faces, or amorphous; sometimes 

 f Yakinikak limestone. ■{ oolitic ; weathers rough ; highly fossil- 

 iferous, Saint Louis horizon ; type on 

 Yakinikak creek, 4 miles west of North 



I fork of Flathead river. 



I Quartzite. 



Algonkian. 



Kintla argillite. 



Sheppard quartzite. 



Siyeh limestone. 



Grinnell argillite. 



Quartzite, massive, coarse, white, or iron- 



' stained ; weathers into roundedbosses ; 



25 feet thick between conformable 



limestone above and unconformable 



1 argillite below. 



Argillite and quartzite, thin-bedded, 

 maroon red, ripple-marked, and sun- 

 cracked, containing casts of salt crys- 

 tals ; also occasional beds of white 

 quartzite and some calcareous ; thick- 

 ness, 800 feet; no upper limit seen; 

 type locality, pyramidal peaks on 49th 

 parallel, at head of Kintla drainage, 

 L foreground of figure 2, plate 50. 



Quartzite, yellow, ferruginous ; thick- 

 ness, 700 feet ± ; overlies extrusive 

 diabase flow ; type locality, cliffs be- 

 tween head of Belly river and central 

 L Flattop mountain. 



Limestone chiefly, but with argillite in- 

 terbedded, usually massive, of mural 

 aspect (plate 49), dark blue or grayish, 

 weathering buff; often characterized 

 by peculiar internal structures and by 

 large concentric growths ; indistinctly 

 fossiliferous, associated with an intru- 

 sive diorite sheet and dikes and with 

 an extrusive diabase flow at its upper 

 surface; thickness, 4,000 feet; type 

 locality, mount Siyeh, at head of Can- 

 yon creek, Swift Current drainage, 

 but equally well exposed in other high 

 peaks (plate 46), mount Gould. 



f Argillite, dark red, shaly, sometimes 

 I arenaceous, ripple-marked, and sun- 

 cracked; thickness, 1,000 to 1,800 feet; 

 type locality, mount Grinnell, at head 

 of Swift Current valley ; also well ex- 

 posed in Appekunny and Kobertson 

 mountains. 



f Argillite, prevailingly gray, black, and 

 greenish ; thin-bedded, ripple-marked, 

 interbedded with white quartzite ; car- 

 ries flattened concretions resembling 

 Appekunny argillite. -J fossils; thickness, 2,000 feet ± ; type 

 locality, Appekunny mountain, north 

 of Swift Current valley ; also generally 



I well exposed in Lewis and Livingston 



L ranges. 



