REPORT OF TEE CHIEF ASTRONOMER 109 



SESSIONAL PAPER No. 25a 



blage of strata may be called the Phillips formation. The exposures are not 

 extensive and the formation crops out nowhere else in the Boundary belt. 

 Two different traverses covered the formation; on both occasions, because 

 of bad weather, the writer was not able to make a thorough examination of these 

 beds. The essential facts of the lithology were obtained but it is not known 

 whether these strata or those of the overlying Poosville formation are fossili- 

 ferous. 



The Phillips consists, for the most part, of about 550 feet of dark, purplish 

 or brownish red, fine-grained to compact metargillite and metasandstone in 

 alternating thin beds. At the base three massive beds of gray quartzitic sand- 

 stone, respectively four, ten, and twenty feet thick, are intercalated. Sun-cracks 

 and ripple-marks are again plentiful. No salt crystal casts were found, though 

 they might, on more prolonged search, be found. Under the microscope, speci- 

 mens of the red rocks proved to be always highly silicious. Small subangular 

 to angular grains of quartz, orthoclase, microperthite, plagioclase, and 

 cherty silica lie embedded in a variable base of sericitic mica and fine grains 

 of magnetite and hematite. The mica is, as usual in the series, abundantly 

 developed in the plane= of bedding. According to the abundance of the once- 

 argillaceous material, the rock may be classed as a metargillite or metasandstone. 

 The total thickness of the formation is about equally divided between these 

 two rock-types. 



The specific gravities of three specimens were found to be 2i-652, 2-674, and 

 2-721. Their average, 2-683, is about the average for the formation as a whole. 



The general composition, colour, and field relations of the Phillips are so 

 similar to those of the upper part of the Kintla formation that one can hardly 

 doubt that the two are in the main, stratigraphic equivalents. The chief litho- 

 logical difference is -chat the Phillips appears to be slightly the more silicious 

 and coarser grained of the two. It may be noted that neither in the Gateway 

 nor in Phillips was any contemporaneous lava discovered. 



Poosville Formation. 



The Phillips formation is conformably overlain by the Poosville, the highest- 

 recognized member of the Galton series. The name is derived from the post 

 office recently opened on Phillips creek. The Poosville outcrops at only one 

 point within the area covered by the Commission map. It there forms the 

 summit of a peak lying three miles east-northeast of Phillips creek cascade 

 at the junction of the creek canyon with the great Kootenay trough. Erosion 

 has removed the upper part of the formation, of which only about 600 feet 

 of beds now remain. How much greater the total thickness may be is not 

 known. 



The formation as exposed at this one locality is essentially made up of 

 thin-bedded, light green, light gray, and greenish gray silicious metargillite 

 bearing thin, more quartzitic, interbeds. The colours of weathering are light 

 gray or brownish gray. Sun-cracks and ripple-marks are common. In field 



