732 L. D. BURLING CAMBRO-ORDOVICIAN NEAR MOUNT ROBSON 



choosing to draw it at the top, where the change from sandstone to lime- 

 stone forming conditions is fairly abrupt, rather than at the more or less 

 transitional calcareous to arenaceous boundary at the base of the Mahto. 



Contact between the Lower Cambrian and pre-Cambrian (§9) 



The contact of the Lower Cambrian sandstones with the pre-Cambrian 

 rocks in the Eobson district is described by AValcott (pages 329-330) as 

 finely shown "to the north, west, south, and southwest of Yellowhead 

 Pass, in Mount McEvoy (Mount Toot Toot), and Yellowhead Mountain, 

 Mount Fitzwilliam (Mount Pelee), and other high points from 8 to 20 

 miles east to the mouth of the Moose Eiver.'' The contact was not 

 studied by the writer, and since difficulties were encountered by AYalcott 

 in drawing the boundary, we lack definite knowledge of the relations 

 between the two series. 



Topographic Features, with Details as to Synonymy and 



• Stratigraphy 



chetaxg cliff (§10) 



Chetang Clift' is a new name applied by AValcott to a cliff southwest of 

 Coleman Brook. The cliffs expose the Chetang limestones, but the con- 

 tact with the underlying formations and the portion up to and including 

 the Alhertella fauna is much better exposed in the summit of Mumm 

 Peak. 



THE EXTIXOUISHER (§11) 



The Extinguisher,^' a small cone of black rock in the Robson glacial 

 cirque, is referred to by Walcott as Billings Butte. Its especial interest 

 lies in the fact that the fauna found in its rocks is, so far as we know, 

 the youngest in the Mount Robson region, and outcrops in place in the 

 beds imm-ediately overlying those forming the summit of Mount Rear- 

 guard (§§ 23c and 23/). It is not improbable that the fauna occurs 

 near the summit of Mount Robson itself (§§ 23c/-e). The Extinguisher 

 beds are much higher stratigraphically than those in the top of Lynx 

 Mountain (§ 24<i). 



MOUXT HITKA (§12) 



Mount Hitka is a name given by Walcott to the high ridge northeast 

 of Mumm Peak and separating that peak from the valley of the Smoky 

 River. From it is derived the name of a formation which he describes 

 as occurring between the Tatay beneath and the "Mumm" above. As we 



^' Coleman : The Canadian Rockies, new and old trails. 



