﻿Book Notices. 329 



In conciseness of form and arrangement of details, it is marked 

 by the clearness and precision which characterize the reports of 

 the able Director of the Geological Survey. 



During the year 1896 the field work was of the usual extensive and 

 practical character. Investigations were made in the most important 

 gold mining regions, viz., Kootanie, Rainy River, the Eastern 

 Townships and Nova Scotia, a deep boring was made in the petroleum 

 district of Athabasca, while questions of less immediate economic 

 importance, but of equal scientific and ultimate value, were studied in 

 all parts of the Dominion. 



In British Columbia Mr. McConnell made a geological examination of 

 the noted mineral region south of the Kootanie River. This whole 

 district is remarkable for the great preponderance of igneous rocks. 

 These are of two distinct series, representing at least two periods 

 of volcanic eruption, the older comprising groups of porphyrites, 

 gabbros and associated eruptives, the latter, an area of granite. The 

 relations of the different members of the older series to one another is 

 best known in the vicinity of Trail Creek. Of these Mr. McConnell 

 says: "At Rossland, the central member of the group is a fine 

 to coarse-grained gabbro, apparently passing in a couple of places into 

 a uralitic granite. The gabbros occupy an irregular shaped area with 

 a length of about four miles and an average width of one mile. * * * 

 The gabbros are fringed with a varying width of augite and uralite- 

 porphyrites and fine-grained green diabases. The passage from the 

 porphyrites to the gabbros is nowhere sharply defined, and the 

 two rocks have apparently originated from the same magma, but have 

 cooled under different conditions. The gabbros and bordering 

 porphyrites are important from an economic standpoint, as most of the 

 ore bodies at present being worked are situated either on or close 

 to their line of junction. The roughly concentric arrangement ot the 

 Trail Creek rocks, and the gradual passage outward from a holo- 

 crystalline central area through semi-crystalline rocks to bedded 

 volcanic fragmentals, suggest an ancient (although now deeply eroded) 

 volcanic centre, situated near the site of the present town of Rossland, 

 from which lavas and ashes deluged the surrounding district. The 

 presence of small bands of coral bearing limestones with the 

 agglomerates and tuffs also makes it probable that a shallow sea 

 existed at the time of the outburst, and that the eruptions were 

 intermittent and continued during a lengthened period." 



The ores contained by these rocks were found to be of a rather low 

 grade, but with better facilities for smelting and transportation, the 

 number of paying lodes would be greatly increased and the value of all 

 enhanced. Mr. McConnell believes that the greater number of the ore 

 deposits occur in the form of replacement veins. 



The newer series of eruptive rocks consists chiefly of granite in 

 varied forms, but owing to its less complex nature the detailed 

 structure is not so important. 



