546 DEPARTMENT OF TEE INTERIOR 



2 GEORGE V., A. 1912 



scale. However, as implied so often in the preceding chapters, the writer 

 believes that a tentative correlation made by the geologist who has actually 

 observed the rocks in the field is better than no correlation at all and in most 

 cases will give safer results than the correlations which would be made by 

 systematists who have no personal knowledge of the ground. For the Skagit 

 range we have the advantage of knowing that there are certain definitely fossili- 

 ferous bands in the different stratified series; the chances for serious error are 

 not nearly so great as in some of the eastern ranges. Among the more impor- 

 tant unsolved problems are those relating to the age of the Custer granite-gneiss, 

 of the older members of the Chilliwack series, of the Skagit volcanics and of 

 the Tamihy series. If the Hozomeen series is really Carboniferous the Custer 

 batholith is almost certainly of Mesozoic, and presumably late .Jurassic, date. 

 But it is conceivable that the country-rocks of this batholith are all of much 

 older date and that this gneissic body may be a small fragment of the pre- 

 Cambrian terrane whence the materials of the Rocky Mountain geosynclinal 

 prism were derived. With the exception of this one body it seems likely that 

 we have no other exposure of those ancient rocks west of the Priest River 

 terrane in the eastern Selkirks. Tempting as it seems to regard the granite- 

 gneiss as a part of the missing pre-Cambrian, the writer is inclined to dismiss 

 that hypothesis and to adhere to the correlation given in the foregoing text, 

 with which the table of preferred correlations should be read:— 



Correlation in the Skagit Range. 



Pleistocene Recent and Glacial (including the gravel plateau of the lower Fraser 



river). 

 Miocene or Pout-Miocene ? . Diabase dikes cutting the Chilliwack batholith. 



rCamptonite dikes cutting the Chilliwack batholith. 



I Syenite-porphyry dikes cutting the Chilliwack series. 

 ,,. „ | Syenite-porphyry (?) dikes (?) cutting the Huntingdon formation. 



Miocene Monzonite stock cutting the Skagit volcanics. 



Chilliwack granodiorite batholith. 



vSlesse diorite stock (?) 



TSkagit volcanic formation. 

 Oligocene (??) \ Skagit harzburgite intrusion. 



[Dunite dikes and gabbro dikes (in part) cutting Chilliwack series. 



Eocene, Huntingdon formation ; unconformable on Chilliwack series, quartzite 



and granite. 



Unconformity. 

 Cretaceous (1) Tamihy series. 



Unconformity. 



{Sumas granite. 

 Sumas diorite. 

 Custer granite-gneiss (possibly pre-Cambrian). 

 Triassic Cultus formation. 



Unconformity. 



TT „ , ., (Vedder greenstone (altered gabbroid rock). 



Upper Carboniferous .... | Chiniwa g ck Volcanic formation. 



Upper Carboniferous (and ( Chilliwack series. 

 older).. . (.Hozomeen series. 



