American Geology, by T. S. Hunt. 405 
Primordial zone, to which, however, palzontologically they ap- 
pear to belong. 
This Quebee group is of considerable economic interest inas- 
much as it is the great metalliferous formation of North America. 
To it belongs the gold which is found along the Appalachian 
chain from Canada to Georgia, together with lead, zine, copper, 
silver, cobalt, nickel, chrome and titanium. ave long since 
called attention to the constant association of the latter metals, 
particularly chrome and nickel, with the ophiolites and magne- 
sian rocks of this series, while they are wanting in similar rocks 
of Laurentian age. (This Joarnal, [2], XXvi, 2% 
the subsequent metamorphism of the strata these metallic mat- 
we conceive to be in a few words the theory of metallic deposits; 
they belong to a period when the primal sediments were yet 
impregnated with metallic compounds which were soluble in the 
permeating waters. The metals of the sedimentary rocks are 
metalliferous character of certain dolomites, which as we have 
shown probably owe their origin to the action of similar alkaline 
Springs upon basins of sea water. wet gst 
The intervention of intense heat, sublimation and similar ny: 
potheses to explain the origin of metallic ores, we conceive to be 
uncalled*for, The solvent powers of solutions of alkaline car- 
