306 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 75 



Sccnella varians Walcott 

 Shaiferia cisina Walcott 

 Bonnia senectus (Billings) 

 Agraitlos unca Walcott 

 Mcsonacis gilbcrti (Meek) 



Feet Meters 



3. Massive-bedded, gray arenaceous limestone 65 19.8 



4. Chocolate brown and grayish, fine-grained sandstone, 



passing at 28 feet (8.5 m.) into a grayish, granular 



sandstone 28 8.5 



5. Massive bed of gray arenaceous limestone, containing 



fragments of OlcncUus 22 6.7 



6. Shaly, brownish sandstone with fragments of Olcnellus. 10 3.0 



Total 160 48.7 



Ross Lake Section 



Ross Lake is situated on the south side of the Canadian Pacific 

 Railw^ay, i mile (1.6 km.) south-southwest of Stephen Station on the 

 Continental Divide. The section was measured on the northeast and 

 northwest sides of the amphitheater above Ross Lake, which is at the 

 north end of the northern spurs of Mount Niblock. The base rests 

 on the purplish-colored massive quartzites of the St. Piran formation 

 on the west slope of the east spur and about 500 feet (152.4 m.) above 

 Ross Lake. The summit as used in this paper is on the east face 

 of the west spur. 



MIDDLE CAMBRIAN 

 Cathedral Formation 



Cliffs of massive-bedded, rough arenaceous limestone rise 

 one above the other to the summit of the ridge. These 

 beds belong mainly to the Cathedral formation, but 

 some collections from the talus would indicate the 

 presence of some beds of the Stephen. 



Ptarmigan Formation^ (including Ross Lake Shale) p^^^ Meter 



1. Thin-bedded, more or less arenaceous and mottled lime- 



stone 155 47-2 



la. Bluish-gray limestone in thin, irregular layers inter- 

 bedded in a greenish siliceous shale 3 .9 



2. Greenish and dark gray, compact siliceous shale, weath- " 



ering to light gray when long exposed. The shale 

 forms compact, solid, hard layers from 2 to 3 feet 

 (.6 to .9 m.) thick that break first into blocks on 

 joint planes and then split up into shale on long ex- 

 posure to the weather 7 2.1 



^ There are now included in the Ptarmigan formation, Nos. id, ic, and if of 

 the Cathedral formation, and la (120 feet [36.6 m.] ) of the subjacent Mount 

 Whyte formation (see Smithsonian Misc. Coll., Vol. 53, No. 5, p. 212, 1908). 



