ii8 The American Geologist. August, 1902. 
of sulphides by reaction between descending waters and prim- 
ary sulphides. 
Until the paper of Spurr's, however, the original sulphide 
deposits have been ascribed to warm deoxidized ascending 
solutions, and so far as the writer is informed Spurr is the 
first to attribute the entire mineralization of a very base series 
of ores to downward moving- currents. 
The arguments used are ingenious and forcible, and the 
facts seem quite largely to favor his hypothesis. The purpose 
of this review is not to criticise nor combat this extreme phase 
of the descension theory, but to call attention to it that it may 
be discussed by others. Still it may be said that the first ob- 
jection to it which arises in the mind of the reader is its in- 
adequacy to account for the sulphur and arsenic so abundant 
in the ores. The heavier metals may be derived from the fer- 
ro-magnesian silicates and from the magnetite; but where on 
the surface and in cold crystalline eruptives do we find sulphur 
and arsenic enough to produce such extensive ore-deposits? 
The paper is very suggestive, and, like all of the produc- 
tions of its talented author, bears the marks of originality and 
truly scientific methods of investigation. h. v. w. 
THE SUTTOX MOUXTAIX. 
There is perhaps no part of the geology of Xorth America 
which has suffered such vicissitudes in geological literature 
as the rocks which were included by the Canadian survey under 
the late Sir William Lagan, in the "Quebec Group." Of that 
group the Sutton mountain rocks in the eastern townships of 
Quebec, have been tossed up and down in the hypothetical 
paleozoic scale, and in hypothetical origin, until they have just 
about "boxed the compass" of geological theory. This is not 
intended as an imputation on the geologists who have studied 
those rocks in the Sutton mountains, but as evidence of the dif- 
ficulties of the geology, and of the imperfect methods pursued 
by them — both inherent in the beginnings of geological w'ork 
in America. Logan, and more especially ^Mather, entertained 
extravagant notions of the efficacy of metamorphism to change 
the nature of rocks, i. e. the aggregate chemical composition. 
The greenstones of Sutton mountain, and of other similar 
ranges in the eastern townships were supposed to have re- 
sulted from a profound alteration of ordinary sediments. That 
