280 SMITHSONIAl^ MISCELLANEOUS COLLECTIONS VOL. 75 



Feet Meters 



At 62 feet (18.9 m.) from the base, numerous frag- 

 ments of trilobite tests occur but are too much broken 

 up to permit recognition of genus or species. 



The fauna near the summit is the same as that in 

 the oolitic limestone in the section of the Mount 

 Whyte formation at McArthur Pass and Mdunt 

 Stephen. 



2. Thin bands of dark gray, arenaceous shale, alternating 



with thin layers of hard, uneven, greenish, brownish- 

 gray sandstone 57 17.4 



This band forms a low cliff on the slopes of Ptarmi- 

 gan, Richardson, and Redoubt Mountains when not 

 covered by talus of the limestone cliffs above. 

 Fauna.— i6oe) : the surface of the sandstones is thickly 

 marked by casts of annelid trails and borings. 



Ptychoparia cere ops Walcott 

 Olenopsis crito Walcott 



3. Fine-grained, dirty-gray to greenish arenaceous shale.. 43 13. i 

 Fauna. — Fragments of trilobites. 



4. Thin-bedded gray, more or less calcareous, hard sand- 



stone 17 5.2 



Fauna. — (35b) : 



Olcnellus canadensis Walcott 

 Mesonacis gilberti (Meek) 

 Bonnia fieldensis (Walcott) 



i 



Total of Mount Whyte formation 342 104.2 



St. Piran Formation 



The upper portion of the St. Piran formation is 

 exposed in the Pass beneath the calcareous sandstones 

 of the Mount Whyte formation and a little to the 

 north on the northeast slope of Ptarmigan Peak the 

 section is exposed down to the pre-Cambrian rocks. 

 The section faces Ptarmigan Lake and may be seen 

 in its entire extent from the southeast side of the lake. 



1. Cross-bedded, gray, brownish-weathering sandstone... 68 20.7 



2. Thick-bedded, hard, light gray, quartzitic cliff-forming 



sandstone 430 131. i 



Fauna. — (60c) : 



Scolithus sp. 



Mesonacis gilberti (Meek) 



3. Shaly and thin-bedded, light, brownish to gray sand- t 



stone 57 17.4 



4. Thick-bedded, light gray, quartzitic, cliff-forming sand- 



stone 230 70.1 



Fauna. — Fine Scolithus occur in immense numbers in many 

 layers that vary from 2 inches to 2 feet (5.1 cm. to 

 .6 m.) in thickness. 



Total of St. Piran formation 785 239.3 



