Wadsworth.] AG? [March 17, 
_It remains for us to examine whether the ore and jaspilite were 
deposited as sediments in situ or are of eruptive origin, since both 
views are held. That the ore and jaspilite are of common origin and 
are inseparable parts of the same formation is universally acknowl- 
edged. ‘Their interdependence is such that the relations of one to 
the country rock give the relations of the other. | 
The question now arises, what are the grounds upon which the 
sedimentary origin of the ore and jaspilite has been urged by differ- 
ent writers. 
The sedimentary origin is advocated on the following grounds: 
« (1) Bog iron ores are forming at the present day. 
(2) On account of the banding or lamination of the ore and jas- 
pilite. 
(3) The bandings show foldings and contortions. 
(4) The jaspilite and ore are jointed and show cleavage. 
(5) The associated rocks are sedimentary and on account of the 
alternation with schists, the ore and jaspilite, as well as the pear 
must be metamorphosed sedimentary rocks. 
(6) The presence of phosphoric acid. 
1°. Taking up the evidence advanced in favor of the sediment- 
ary origin of the jaspilite and ore in order, we meet first the form- 
ation of limonite in modern times. It is urged, since limonite is 
now formed, that all workable iron ore must have been produced in 
the same way. Iron ore is produced at the present day by volcanic 
eruption and by sublimation. Would it then be proper for us to 
claim that since iron is and has been placed on the earth’s surface 
in modern times by eruption and sublimation, that all workable iron ore 
in past times was produced in one or both of these ways? Certainly, 
as fit and right as it is for others to hold, that because bog iron is and 
has formed on the surface, that hence all past ores must have been 
formed as bog ore. However, neither of these arguments appears 
to us to be sound, for the only correet method is to study the deposit 
in question and decide as to its origin from the facts it presents. It 
is to be distinctly understood that we are talking only about the de- 
posits in the Marquette district that we have personally studied, and 
not about others there or those of other districts. 
It seems that those who hold to the sedimentary origin of iron ores 
draw a line between those deposits which can be worked with profit 
and those that can not, in the present state of commerce. Nature, 
according to them, evidently drew the line between eruptive and non- 
