402 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
For these, it would seem that some of the least metamorphosed 
sandstones present the best opportunities. 
The petrographic character of the sediments, the contact meta¬ 
morphism near granite bosses, the character of these intrusions, all 
must receive careful treatment before the history of the series can 
be well understood. An examination of the metamorphism of the 
sediments will throw some light upon the origin of both veins and 
gold, and Upon the history of the latter. The so-Called pre-Cam¬ 
brian volcanics in the eastern part of the Province also may have 
some connection with the auriferous series, and deserves the atten¬ 
tion which is being paid to the old extrusions of the Atlantic coast 
farther south. 
In connection with the occurrence of the gold, the reason for its 
prevalence in the argillaceous members of the formation, which is 
not so simple as that of the frequency of veins in the same rocks, 
may receive at the hands of another an answer different from the 
one given here. The age, progress, and extent of the denudation 
of the series has yet to be studied, and may throw light upon the 
distribution or concentration of the gold which has been removed 
during the process. Finally, the nature, origin, and direction of 
the two great orogenic forces which have influenced the series have 
not been studied with the care they deserve. 
