84 



The geology of Rossland centres around a mass of 

 monzonite which is rudely oval in form with the east 

 and west axis about five miles (8 km.) in length. The 

 mass is intrusive into the rocks of the Rossland group, 

 which has been subdivided into a sedimentary and igneous 



Table of Formations. 



Quarternary. ... Glacial and Recent. 



Tertiary Pulaskite. 



f Post- Jurassic ? Lamprophyric dykes. 



Serpentine. 



Nelson granodiorite and granite 

 porphyry. 



Mesozoic -{Jurassic ? Porphyritic monzonite. 



Diorite porphyrite. 

 Monzonite. 



Triassic ? Volcanic agglomerate. 



/Carboniferous Augite porphyrite. 



Palaeozoic \ (Rossland group). Mount Roberts formation. 



Carhoniferous. 



Mount Roberts formation — The Mount Roberts 

 formation is developed chiefly in two bands, the broader 

 one lying on the western slopes of Red mountain, while 

 the narrower one lies further to the west, separated by 

 a band of igneous rocks. The formation consists of 

 black slates, in part carbonaceous, with arenaceous and 

 calcareous varieties interbedded with lighter coloured 

 types. There is a frequent interbanding of darker varieties 

 with lighter coloured and more siliceous types some of 

 which are probably of tufaceous origin. Fossils have 

 been collected in one locality and though poorly preserved 

 have been identified as Carboniferous types. 



The strike of the formation is northerly with a general 

 dip to the west which steepens on going westward. In 

 the western band the beds are vertical, which is probably 

 due to a fault. The sediments are extensively faulted 

 in an east and west direction with throws varying from a 

 fraction of an inch to several feet. Breccias are common 

 along the contact of the sediments with the granodiorite 

 and porphyrite. 



