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THF KAWISHIWIN AGGLOMERATE AT ELY, MINN. 
N. H. WINcHELL, Minneapolis. 
It nas been stated that the gneisses and schists of. the Archean, 
in Minnesota, terminate upwardly by a great non-conformity with 
the overlying Taconic. It has also been shown that the upper- 
most member of the Archean is the Keewatin, a series of schists, 
graywackes and variously reconstructed gneissic rocks. It has 
been shown, further, that the youngest member of the Keewatin 
is the pronounced ‘‘greenstone’’ stage, in which occur the iron 
ores of the Vermilion iron range in Minnesota. This phase of 
the Keewatin has been designated specially Kaw/ishiwin from the 
Kawishiwi river, on whose upper courses these rocks are exposed 
in favorable position for study. It has also been shown that 
these rocks have been subjected to great pressure, upheaval, 
shearing and fracture, resulting in very tortuous structures and 
complication of physical features. 
It has been a subject of much study and no little variety of 
opinion, as to the origin of these greenstones,—are they plutonic 
rocks that have been subjected to ‘“‘dynamic metamorphism” and 
thus caused to show the semi-decayed conditions that mark their 
mineral constituents, or are they sediments consolidated or 
‘‘metamorphosed”’ so as to have lost their original structures and 
composition? Or, again, are they the result of a ‘‘crenitic”’ pro- 
cess, as suggested by the late T. Sterry Hunt. by which they are 
the reliquize of mineral waters circulating through the crust of the 
earth, left at the surface on evaporation? Or are they the rem- 
nants of the primary basic doleritic crust of the earth, produced 
by the solidification of the primeval molten mass? 
They are not the remnants of the first cooled doleritic crust be- 
cause they are younger than all the other stratigraphic parts of the 
Archean. They are separated by many thousands of feet of strata 
from the basal gneisses which are called distinctively Laurentian. 
They are not ‘‘crenitic’” recks, if the acid basal gneisses are 
crenitic, for they contain in predominating amounts those very 
elements which are first and easiest dissolved by heated waters, 
and which could not be left as reliquize on evaporation—and also 
because in order to form ¢éhese and the acid basal gneisses there 
would have to be a reversal of the respective solubilities of the acidic 
and the basic minerals concerned, between the date of the forma- 
tion of the gneisses and the date of the greenstones, which is 
