The Barahoo Iron Ore. — Winchell. 251 
the Sioux quartz) t(.' and the Barron County quartzytc arc all 
on practically the same stratigraphic horizon, and the same 
horizon as the New Ulm quartzytc. 
4. Hence the Baraboo iron ore is later than the Animikie, 
and the Baralioo conglomerate and quartzytc are the sedimen- 
tary equivalents of the Puckwunge conglomerate and quart- 
zytc. 
5. Therefore the Baraboo iron ore being later than the 
red rhyolyte is in the proper stratigraphic place to be cotempor- 
ary with the Manitou igneous epoch of the Keweenawan, 
and was accumulated under conditions that were identical with 
those shown by the writer to have prevailed when the ores of 
the Vermilion range and of the Mesabi range were deposited. 
The writer has described the Puckwunge conglomerate as 
the fragmental base of the Manitou epoch of the Keweenawan, 
and non-confonnable on the Cabotian, and also non-conforma- 
ble (owing to subsidence of the lake Superior region) on sev- 
eral older formations. The subsidence which was later and 
is well known as the cause of such non-confonnity of the 
Upper Cambrian on older formations (even on Archean) 
seems to have begun far back in the Keweenawan and to 
have produced a progressive non-conformity of the Manitou 
rocks (or their associated fragmentals) on the still older rocks. 
The author of this volume has made an important contri- 
bution to the question of the origin of iron ore, in showing that 
the Baraboo iron was not the product of metasomatic alteration 
of other rocks by the agency of underground water, and hence, 
owing to the common links that bind it with the ore of other 
iron ranges, that probably none of the lake Superior ores were 
due to any important degree, to the action of underground 
waters. Still such waters have played doubtless an important 
part in changing the ore from one mineral condition to an- 
other, and perhaps to some extent in transporting it and con- 
centrating it in certain strata where heat and pressure have 
co-operated to produce crystalline hematite. The author is to 
be congratulated for the thorough and independent manner of 
this investigation. 
It would have l)een a fortunate thing if he had been equally 
indepeiKlent anil thorough is assigning the Baralxx> ore to its 
stratigraphic place. He has tentatively put it somewhere in 
