REPORT OF TEE CHIEF ASTRONOMER 165 



SESSIONAL PAPER No. 25a 



Nevertheless, in the Summit series there is a very thick group of ferru- 

 ginous, silicious sediments conformably overlying a yet thicker group of gray 

 silicious sediments not specially ferruginous. The former grotip, the Beehive 

 quartzite (7,000 feet thick), relatively thin-bedded, ripple-marked, and charged 

 with thin interbeds of dark gray to brown argillite, is essentially similar to the 

 Kitchener quartzite (7,400 feet thick), and are so shown in the correlation table 

 and Plate 20. Plate 21 probably errs in correlating the Dgwdney with the 

 Kitchener; thus representing the writer's early view, abandoned since this dia- 

 gram was drawn. 



The Lone Star schists are to be correlated with the Moyie formation. 

 Immediately beneath the Beehive quartzite is the remarkably rippled, white 

 Eipple quartzite (1,650 feet thick), succeeded below by the gray Dewdney 

 quartzite (2,000 feet thick), the gray Wolf grit and the huge mass of gray 

 and greenish-gray Honk argillites, sandstones and interbedded conglomerates. 

 Many of the quartzite beds of this huge group of gray-tinted sediments cannot, 

 in ledge or hand-specimen, be distinguished from the dominant Creston 

 quartzite. 



In favour of correlating the Creston quartzite with these formations, exclud- 

 ing the Eipple quartzite, is the fact that the Dewdney, "Wolf and Monk formations 

 are, like the Creston, composed of dominant quartz, with which much essential 

 feldspar is usually mixed. In both the Purcell (Kitchener and Creston) and 

 Summit series (Beehive to Wolf inclusive), this feldspar is very commonly 

 microperthite, finely lamellated in normal fashion. The recurrence of this 

 feldspar, here essential yet so uncommon in such thick sedimentary masses, 

 gives excellent corroboration of the conclusion arrived at in the field that 

 within the Summit series, the equivalent of the Creston quartzite includes the 

 relatively non-ferruginous formations below the Eipple quartzite, Ihe feldspar 

 is a kind of fossil. The base of this group, equivalent to the Creston as 

 exposed in the Boundary belt, probably occurs some 2,500 feet below the summit 

 of the Monk formation. 



The equivalents of the lower and greater part of the Monk formation of 

 the great Irene Volcanic formation and of the thick basal Irene conglomerate 

 have nowhere, within the Purcell or Eocky Mountain systems, been thrust up 

 to view in the Boundary belt. 



If the foregoing correlation is correct, the monocline of the Selkirk range 

 furnishes a key to the stratigraphy of the whole geosynclinal. The base of the 

 geosynclinal prism is seen at the unconformable contact of the Priest Eiver 

 schists on Monk creek. The uppermost beds of the prism have, in all the 

 eastern mountain ranges, been eroded away as a result of the repeated orogenic 

 uplifts which have occurred since Cambrian time. In the Selkirks the whole 

 prism may be represented, but the extreme mashing and metamorphisrn of the 

 upper beds have made their stratigraphic relations at the Porty-ninth Parallel 

 very obscure. 



