Correspondence. 383 
appear when we search for the remainH of the Hupposed older carbonate, 
and when wo find the country rock does not afford good reason to have 
expected the (lepo.sition of any carbonate ; and also when we search 
for the remaining ingredients which the assumed nietasomatic process 
may have left in the ore." 
This implies that no carbonate of iron is found associated with the 
iron ores of Vermilion lake. This is not the case. Professor Irving 
found as early as 1885 finely laminated rocks which bear a large per- 
centage of iron carbonate immediately adjacent to the iron ores which 
occur near Tower. Indeed, in his article on the origin of the iron 
ores in the American Journal of Science, he particularly emphasizes 
the fact of the presence of iron carbonate in these Vermilion lake ores, 
and in some detail describes the changes to which the rock has been 
subject. Among other facts is mentioned the formation of inm oxides 
pseudomorphous after iron carbonate. Analysis by professor W. 
W. Daniells shows that the amount of iron carbonate in one 
specimen collected by professor Irving in the summer of 1885 is as 
high as 25 per cent. It was such facts as this, combined with many 
other points of similarity between the Vermilion lake iron-bearing 
beds and the other important lake Superior iron-bearing horizons, upon 
which he based his argument for a like genesis of them. 
The article in the American Geologist also implies that I have 
maintained an origin for the ores of Vermilion lake like that of the 
Penokee-Gogebic country. I have refrained from expressing an opin- 
ion upon that question. I only say in the American Journal for Jan- 
uary, 1889, "that it would be an interesting illustration of the uniform- 
ity of Nature's processes, if future investigations should show that the 
iron ores in the other regions of the lake Superior country have an 
origin like those of the Penokee-Gogebic series." 
It is not my purpose here to discuss the opinions expressed by the 
authors in the paper, but merely to correct the misconceptions which 
are contained in the paper as to the work and opinions of the late pro- 
fessor Irving. 
C. R. VanHise. 
Madison, Wis., Nov. 9, 1889. 
Prof. Van Hise calls attention to the fact of the recognition by Prof. 
Irving of the unconformity between the Animike and the underlying 
gneisses and schists in the vicinity of Gunflint lake, and refers to Prof. 
Irving' s general sections of the lake Superior basin (Copper-bearing 
rocks of lake Superior, p. 416), and to his descriptions in the .-Ijm. 
Jour. Sci. for 1887, p. 201. Prof. Van Hise quotes these as evidence 
that the statements made in the November Geolocust,' to the efi'ect 
that Prof. Irving did not recognize the two great iron-bearing horizons 
in the northwest and in his attempts to account for the existence of 
^ On a possible chemical origin of the iron ores of the Keewatin in 
northeastern Minnesota, p. 291. 
