•48 The American Geologist. July, 1897 
t^cts on a cold rock it is chilled and crystallizes finer at the 
immediate contact. No such phenomena are found in tliese 
contacts. 
We conclude, therefore, a* already stated, that the trans- 
ition from tlie crystalline schists to the gneiss and granite 
was of the nature of a gradual conformable change, accompa- 
nied by silicification, and by a change of the schists them- 
selves to gneiss, in the first place, and finall}^ to granite by 
hydro-thermal fusion, and that the granitic rock penetrated 
the schists by generation in them of the granitic minerals in 
the first place, and later, or nearer the seat of the greater heat, 
by actual intrusion in a molten form. 
2. We come now to the second point to which I wish to 
call your attention, viz., the nature and relations of the Stuntz 
(:on(/lonierate to Yerntilion lake. 
This conglomerate forms a large island near the south shore 
of the lake, and is named from this island. It also spreads 
east and west for several miles, appearing on the mainland. 
It is a rather curious formation, as its pebbles consist almost 
wholly of one kind of rock, and that of a kind not known in 
the region in sufficient amount to have furnished these pebbles, 
viz., a gray felsyte, or quartz porphyr3% The Minnesota sur- 
vey has reported on this conglomerate, but without reaching 
an}' conclusion as to its true nature and origin, although lat- 
terly somewhat inclined to favor the idea of eruptive origin 
for the mass, the pebbles being, under that hypothesis, of the 
nature, originally of volcanic bombs, and the cement of the 
nature of volcanic ash. This view, however, has never been 
published. 
About a year ago a paper was published in tlie Transaction 
of the American Institute of mining engineers,* whose autliors 
proposed a new and remarkable hypothesis for the origin of 
this conglomerate, which if true, taken in connection with all 
the attendant consequences, as detailed by them, would require 
very important, and even sweeping changes in the geology of 
the region as it has been supposed to exist, and as reported by 
the Minnesota survey. They advocate the view tliat this rock 
is not a conglomerate, but a breccia. They consider it as a 
*Smyth and Finlay. Geological Structure of the western part of the 
Vermilion range, Minnesota. Tran. Am. Inst. Min. Eng., Atlanta 
meeting, pp. 51, 1895. 
