REPORT OF THE CHIEF ASTRONOMER 385 



SESSIONAL PAPER No. 25a 



can be seen in them, but the grand features of their structural relationship 

 are lost through the effects of the later igneous intrusions. Some of the 

 limestone inclusions are to be explained as squeezed intercalated beds. 

 Under pressure, the limestone flows and from a thin bed a line of inclusion- 

 like lenses may be formed. This series of pyroclastic and volcanic rocks 

 seems to have been formed immediately after the sedimentary series, and 

 is therefore probably Palaeozoic. In the Palaeozoic formations of the Kam- 

 loops district, also, green effusive rocks occur. 



' As already remarked some of the serpentine appears to be of later 

 age than this series.' 



The problem of correlation of the Phoenix volcanics with the standard 

 systems of rocks is practically the same as that found in the Eossland moun- 

 tains, where the Rossland volcanic group was placed by McConnell and Brock 

 in the Carboniferous. The view expressed in the last chapter, that the great 

 bulk of the Rossland volcanics is of Mesozoic age, is founded on arguments 

 which are in part of the same nature as those deducible from the facts recorded 

 by Mr. Brock for the Phoenix area. The present writer's very limited knowledge 

 of the belt between Grand Forks and Midway forbids his taking any definite 

 position different from that taken by Mr. Brock. Yet it seems possible that 

 the Phcenix group also is largely of Mesozoic age and contemporaneous with 

 the similar andesitic members of the Rossland group. Mr. Brock has not 

 reported any latitic phases here, such as are so abundant in the eastern district, 

 but their presence in limited quantities may be declared when chemical analysis 

 ha3 been applied to the ' Boundary Creek district ' formation. In any case, 

 however, the resemblance of the Phcenix and Rossland groups lithologically and 

 the parallelism of their dynamic histories are sufficiently patent to make their 

 direct correlation highly probable. The abundance and nature of limestone 

 and argillitic fragments in the agglomerates of the Phoenix group suggest 

 that those sediments were thoroughly consolidated, if not metamorphosed before 

 the major eruptions took place. This leads one to suspect that the Phoenix 

 volcanics are really in distinct unconformity to the Attwood series, as the 

 Rossland volcanics are unconformable upon the Carboniferous rocks of Little 

 Sheep creek and upon the formations of the Pend D'Oreille group. 



As a suggestion, rather than as a conclusion, the writer has therefore 

 correlated the Phcenix group with the Rossland group in its middle part and 

 thus holds the hypothesis that both belong to the Mesozoic. The question is, 

 however, in the writer's opinion, wide open. 



Serpentine. 



Many bodies of serpentine have been mapped in the Boundary Creek 



district. Mr. Brock has given a short account of them in immediate connection 



with the Attwood series of argillites, etc. He writes (Report for 1902, p. 96) : — 



' The serpentine occurs as bands and masses cutting these sedimentary 



rocks. Tbe intrusive nature of the serpentine is shown in -the way in 



25a — vol. ii — 25 



