742 L. D. BURLING CAMBRO-ORDOVICIAX NEAR MOUNT ROBSON 



(§ sob.) Xow, the formation occupying this position in the contin- 

 uous and fossiliferous section of the "Tah/^ Mahto, "Hota/' and Chetang 

 formations (§§ 16 and 32c) exposed in Mumm Peak is a massive 300- 

 foot cliff-forming, gray arenaceous limestone, with transitional elastics 

 at the base ; and it is this bed which AValcott took to be a younger lime- 

 stone, 3,400 feet higher in the section than the "Hota,^' and to which he 

 gave the name "Mumm limestone" (§§ 266 and 32c). 



(§ 30c.) Walcott (page 339) refers to the "Hota"' as the "Xew Lower 

 Cambrian subfauna" described by him in the preceding number of the 

 Miscellaneous Collections (volume 57, number 11). This fauna was 

 mostly collected from drift blocks on the surface of Mural Glacier, but 

 Walcott (legend to plate 59) locates the horizon in the cliffs just above 

 the glacier. 



(§ oOd.) A section of the beds in this locality, beginning at the gla- 

 cier, passes up through the "Tah" into the Mahto sandstones, and shows 

 (a) that the beds in the position indicated by Walcott lie approximately 

 2,500 feet below the "Hota,"' and (h) that the general description given 

 for the lithology of the ^"Hota" was derived from an exposure of the 

 "Tall" ; for, unless Walcott^s "Hota" is- incorrectly defined as underlying 

 the Chetang and really lies 2,500 feet below that formation and beneath 

 a massive series of quartzites, the beds containing the "Xew Lower Cam- 

 brian subfauna"" can in no way be referred to the "Hota" and must be 

 referred to the "Tah" (see § 32). 



(§ 30e.) Walcott places the "Hota"* formation in the Lower Cambrian, 

 but the OleneUus, on which this correlation is based, occurs in the "Tah" 

 at a 2)lace where the latter had been identified as "Hota." Xaturally, 

 therefore, the line between the LoAver and Middle Cambrian was drawn 

 at the toj) of the "Hota"; but we have found typical Middle Cambrian 

 fossils in the base of the "Hota" without OleneUus, and have drawn the 

 Lower-Middle Cambrian boundary below (§§ 8, 30/, 31c, 32(i, 32e). 



(§30/.) It will be noticed that our generalized sections (§2) gives 

 the "Hota" (Adolphus) a thickness 400 feet less than Walcott, and it 

 should be stated that neither the addition of 400 feet from the overlying 

 Chetang, nor the addition of any number of feet up to one thousand, 

 apj)arently, from the underlying Mahto would add Lower Cambrian 

 fossils to the "Hota," though it would explain the reference to quartzites 

 in Walcott 's description of- the "Hota." 



(§ 30^.) Lest any one should think that the differences between Wal- 

 cott's interpretation and my own are due to failure correctly to identify 

 his formations, it may be stated that his "Hota" is the formation under- 

 lying the Chetang, however it is described lithologically, and the Chetang 



