NO. 12 CAMBRIAN FORMATIONS ROBSON PEAK DISTRICT 33 1 



Oi'dovician. — The Robson formation (pi. 58, fig. i,) is considered 

 to extend from the summit of Robson some 3,000 feet down. This 

 estimate is based on the view obtained from BilHngs Butte (pi. 5.8, 

 fig. 2) of the Upper Cambrian beds as they extend along the base 

 of Mount Resplendent into Robson. There is abundant opportunity 

 for error as to the actual thickness of the strata, but I think it is on 

 the side of too low an estimate and that in the future a greater 

 thickness will be assigned to the Ordovician of the Robson massif. 

 One element that could not be estimated for is the faults that have 

 dropped and tipped the mass of strata forming the Helmet between 

 Robson and lyatunga. 



NOMENCLATURE 



Although not an original explorer of the Robson Peak District, it 

 fell to my lot to be the first to study the geologic section, and in this 

 connection it was necessary to apply additional names in order to 

 properly locate, describe, and name the geologic formations. 



Changes in }iaincs. — Of the names previously used and printed on 

 the Wheeler map of 1912,' I thought it might be well to change the 

 following : 



i. Ptarmigan Peak to Titkana (bird) Peak. 



2. Rearguard to lyatunga (black rock) Mountain. 



3. Extinguisher to Billings Butte. 



4. Robson Glacier to Hunga (chief) Glacier. 



5. Mount Robson to Robson Peak. 



6. East Branch Moose River to Moose River. 



7. West Branch Moose River to Hihuna (owl) River. 



8. ]\Iount Toot-toot to McEvoy Mountain. 



My reasons for the above changes are : 



1. The name " Ptarmigan " has been applied to a mountain and a 

 lake north of Laggan in Alberta. 



2. " Rearguard " does not appear to be an appropriate name for 

 one of the great portals of the main glacier. 



3. " Extinguisher " was given by Coleman to a butte that is of the 

 greatest geologic importance as it is made up of rocks containing 

 the finest Cambro-Ordovician fauna yet known in Western Canada. 

 The name " Billings " is proposed for this butte in honor of E. 

 Billings, the distinguished Canadian paleontologist, who described 

 the famous Cambro-Ordovician fauna of Point Levis, Province of 

 Quebec, and Western Newfoundland. 



' Canadian Alpine Journal. Vol. 4, 1912. 



