Chemical Origin of Iron Ores, Etc. — Winchell. 291 
Segregation of communes. 
Commonwealths. 
( Agriculture. 
Resources, 
■j Industries. 
I Manufactories. 
t Transportation 
In many of our states man now begins to occupy virgin soil ; 
here can be seen the very beginning of civilization ; its gradual 
development and all its varied phenomena can yet be perman- 
ently fixed and gathered, constituting a treasure the like of 
which is not in possession now of either individual or com- 
monwealth. 
ON A POSSIBLE CHEMICAL ORIGIN OF THE IRON ORES OF 
THE KEEWATIN IN MINNESOTA. 
Read Sept. 2, 1889, at the Toronto meeting of the American Association 
for the Advancement of Science . 
By N. H. Winchell and H. V. Winchell. 
The proper understanding of the limits of this discussion 
requires a brief statement of some recent stratigraphic 
determinations. It is evident that the papers of the late 
Prof. R. D. Irving ' and of Prof. C. R. Van Hise,^ while in 
the main considering the problem from the point of view of 
the "Huronian," have also embraced in the scope of the phe- 
nomena cited, a group of strata much older, which lie every- 
where' unconformably under the Huronian, and which present 
a series of facts which are distinct from those appertaining to 
the Huronian as found in the Penokee-Gogebic and Mesabi 
regions. The confounding of two formations, and the placing 
in one category the chemical and structural phenomena that 
are separated into two series by a great time interval, and by 
structural unconformity, have so complicated the problem 
that hitherto no theory has been found capable of cov- 
ering all the facts. The existence of this widespread uncon- 
formity has been shown in recent Reports on the geology of 
the northwest by A. C. Lawson, A. Winchell, and by the 
writers ; and latterly it was also recognized by Irving (7th An. 
^ Am. Jour. Sci. (iii.) xxxii. 255. 
^Am. Jour. Sci. (in.) xxxvii. 32. 
^Compare the Seventeenth annual report of the Minnesota survov, 
pp. 42-45. 
