330 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 57 



shown in Mount McEvoy and Yellowhead Mountain, Mount Fitz- 

 william, and other high points from eight to twenty miles (12.8 km. 

 to 32 km.) east of the mouth of the Moose River. 



Location of the section. — The location of the section is graphically 

 shown by the photographs reproduced on plates 55-59. These will 

 enable the future student of the geology of the region to recognize 

 the localities and the general position of the formation. 



Lozi'er Cmnhrian. — In figure i, plate 55, the lowest Cambrian 

 beds of the Robson section are shown at the foot of Tab Peak. 

 These are more clearly seen in the text figure No. 11. In figure 2, 

 plate 55, the sandstones of the Tab formation and of the lower beds 

 of the superjacent Mahto formation slope to the southwest and pass 

 beneath Mahto Mountain, while the higher beds of the Mahto for- 

 mation form the south face of the mountain. In figure i, plate 56, 

 the masses of strata forming Tah Peak and ]\Iahto Mountain are 

 clearly outlined. 



The Hota formation on the w-est and southwest slope of Mahto 

 Mountain is shown on the left side of figure 2, plate 56. It forms 

 the slope in the foreground, also in the ridge back, and passes 

 beneath limestones of the Chetang formation at Coleman Brook. 



Middle Cambrian. — The Chetang limestones rest on the Hota for- 

 mations on the west side of Coleman Brook and form the Chetang 

 Cliff above the brook (pi. 56, fig. 2; pi. 57, fig. i) for 900 feet. 

 Above, the siliceous limestones of the Tatay formation form 

 the Tatay Cliffs, and west of the latter the thin-bedded arenaceous 

 limestones and shales of the Hitka formation carry the section up 

 to the massive-bedded arenaceous limestones of the Mumm forma- 

 tion. The latter occur on the westward slope of the ridge east- 

 northeast of the lower end of Lake Adolphus. All these Middle 

 Cambrian strata occur between Coleman Brook and the west slope 

 of the point ( marked " x " on pi. 56, fig. 2 ; pi. 57, fig. i ) northeast 

 of the summit of Titkana Peak. 



The Titkana formation forms the north and west slopes of Tit- 

 kana Peak, and extends over the summit toward Snowbird Pass 

 (pi. 57, fig. 2) and the summit of Titkana Peak as seen in figure i, 

 plate 58. 



The Middle Cambrian formations also form the mountains west 

 of the Smoky River, as beautifully shown by figure i. plate 57. 



Upper Cambrian. — The Lynx formation of the Upper Cambrian 

 begins on the south slope of Titkana Peak near Snowbird Pass, and 

 extends over PhilHps Mountain (pi. 57, fig. 2), and into the base of 

 Billings Butte. 



