336 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 57 



STRATIGRAPHIC SECTION FROM ROBSON PEAK 

 NORTH-NORTHWEST TO MOOSE PASS 



ORDOVICIAN SYSTEM ^^^ 



ROBSON LIMESTONES.— Light-gray or dove-colored and bluish-gray 

 thin-bedded limestones, forming massive strata on cliff ex- 

 posures 3,000 



The upper 1,500 feet of Robson Peak are practically 

 inaccessible. The limestones appear to be more massive-bedded 

 and arenaceous than the strata below. They weather like 

 the great arenaceous limestones of the Kicking Horse Pass 

 section 150 miles to the south. Large blocks of the arenaceous 

 and dolomitic buff-weathering limestone, also siliceous and 

 calcareous gray shale with buff-weathering magnesian lime- 

 stone in thin layers, were brought down from high up on 

 Mount Robson by the central moraine of Hunga Glacier. 



There is no known well-defined lithological break between the 

 Ordovician and the Cambrian. A line is now tentatively drawn 

 in a series of thin-bedded and shaly limestones, at Billings 

 Butte, where there is a commingling of the lower Ordovician 

 and Upper Cambrian faunas. 

 Fauna. — (6iu) In the gray thin-bedded limestones brought down 

 by Chupo Glacier on the northeast slope of Robson Peak four 

 species of fossils were found that indicate an horizon very close 

 to if not within the base of the Ordovician : 



Lingulella cf. L. manticula White 



Acrotrcta sp. undt. 



HyoUthes sp. undt. 



Ptychoparia sp. undt. 

 In Billings Butte (Locality 6in) in the upper part of the 

 shaly limestone the fossils are distorted. The collection 

 includes a Lingulepis that appears to be identical with Lin- 

 gulella (Lingulepis) acuminata Conrad, and a species of 

 Asaphus the fragments of which indicate a rather large species. 

 Below the Lingulepis zone, limestones occur interbedded in 

 the shaly layers that indicate by the contained fossils the base 

 of the Ordovician. Locality 6iq^ is in Billings Butte which rises 

 above Hunga Glacier 2.5 miles (4 km.) north of the summit 

 of Mount Resplendent (fig. 2, pi. 58). The following fauna 

 was collected : 



Lingulella cf. L. isse Walcott Hungia billingsi n. sp. 



Acrothele sp. undt. Trior thrus sp. undt. 



Acrotreta cf. A. sagittalis Salter Solenopleura sp. undt. 



Eoorthis desmopleura Meek Peltura (Pygidia) 



Eoorthis ? Apatocephalus 



Syntrophia nundina Walcott Chuangia robsonensis n. sp. 



Bellerophon sp. undt.^ lUcenurus n. sp. (a) 



Orthoceras sp. undt. ' Illcenurus n. sp. (b) 



Agnostus sp. undt. 



