316 DEPARTMENT OF THE INTERIOR 



. 2 GEORGE V, A. 1912 



Finally, a three-foot, north-south, vertical dike of highly amygdaloidal 

 basalt, cutting the Pend D'Oreille phyllite about fifty yards wesit of the mouth 

 of Twelve-mile creek, may be noted. 



Belative Ages of the Eruptive Bodies. 



The entire lack of paleontological evidence within the ten-mile belt makes 

 it impossible to form a full chronological column for the formations occurring 

 in this part of the Selkirks. It may be recalled that the Priest Biver terrane 

 unconfonnably underlies the great Surnmit series, with a part of which (the 

 Beehive formation) the Kitchener quartzite is believed to be equivalent. The 

 Pend D'Oreille group overlies, with apparent conformity, the Summit series 

 and, as will be further indicated in the next chapter, unconformably underlies 

 the Bossland and Beaver Mountain groups of sediments and volcanics. The 

 relative ages of the igneous rocks can be partly indicated through their relations 

 to these sedimentary groups as well as through their relations to each other. 

 The observed facts may be briefly summarized. 



The intensely crushed Bykert granite batholith cuts the Priest Biver terrane, 

 including bodies of metamorphosed hornblende gabbro which themselves cut the 

 schists and quartzites of the terrane. The uncrushed and very rarely sheared 

 Bayonne batholith cuts formations belonging to the Priest Biver terrane and 

 Summit series respectively. The satellitic stocks believed to be contemporaneous 

 with the Bayonne batholith cut the Pend D'Oreille group and one of them — the 

 Bunker Hill stock — seems to cut the older members of the Bossland volcanic 

 group. The Salmon river monzonite istock cuts the Pend D'Oreille schists 

 and limestone. The abnormal hornblende granite at Corn creek cuts the 

 Kitchener quartzite and is tentatively correlated with the Purcell sills. The 

 minettes, kersantites, camptonites, and odinites cut the Pend D'Oreille schists 

 or limestones and probably also cut the Bossland volcanics, since similar 

 lampvophyres cut the Bossland monzonite stock which is almost certainly of 

 the same general age as many of the Bossland lava flows. The peculiar por- 

 phyritic olivine syenite cuts the Bossland volcanics; in the next chapter the 

 correlation of this syenite with the minettes will be indicated. The Sheppard 

 granite cuts the Trail granodiorite which itself cuts the older members of the 

 Bossland volcanics. Since a half dozen of the principal formations in these 

 Selkirk mountains are more directly associated with fossiliferous sediments in 

 the mountains across the Columbia river, the discussion of the final correlation 

 of the Selkrrk rocks will be postponed to the chapter dealing with- the geology 

 of the Bossland mountains. At this point it will be sufficient to anticipate 

 that discussion by tabulating the Selkirk formations in their probable order 

 of age: — 



